The Testament of Sister New Devil (Shinmai Maou no Testament) is a bold, ecchi action anime that blends supernatural battles, harem romance, and family drama. The story follows Basara Toujou, a young man from a family of heroes who must protect his two new stepsisters, Mio and Maria, who are secretly a demon lord and a succubus. He forms a “master-servant contract” with them to strengthen their powers, but the contract requires intimate acts to maintain. The series balances its ecchi elements with genuine action and emotional stakes as Basara fights to protect his new family.
The series is defined by its core themes: a power system rooted in the “master-servant contract” and the bonds between the characters, where trust and intimacy are central to unlocking true strength. Basara is a quintessential underdog—a young man who is thrust into a dangerous world and must protect his family while navigating the complexities of his relationships. The Testament of Sister New Devil masterfully subverts expectations by presenting what appears to be a simple ecchi harem and gradually revealing a deeper narrative about family, loyalty, and the sacrifices required to protect those you love. It is a series that understands the power of a bond.
For fans of The Testament of Sister New Devil, finding similar anime can be a challenge. The series occupies a unique space—part ecchi harem, part supernatural action, part family drama. Yet, many underrated series share its core DNA: a focus on a male protagonist who forms intimate bonds with powerful female characters, an exploration of a power system rooted in those bonds, and a willingness to blend action, comedy, and genuine emotional depth. These shows deserve far more attention for their entertainment value, their character development, and their refusal to provide easy answers.
Here are 15 underrated anime that capture the spirit of The Testament of Sister New Devil.
1. High School DxD (2012)
- Streaming Availability: Crunchyroll, Funimation
- Rating: MAL: 7.3
- Episodes: 12 (Season 1)
- Studio: TNK
- Notable Staff: Based on the light novel series by Ichiei Ishibumi.
Plot Summary: Issei Hyoudou, a perverted high school student, is killed on his first date and resurrected as a devil by Rias Gremory, a beautiful demon princess. He becomes her servant and fights in supernatural battles.
Similarities to The Testament of Sister New Devil: Both are ecchi harem action series about a male protagonist who gains supernatural powers through a bond with powerful female characters. The focus is on the blend of action, comedy, and romance, with a power system tied to the relationships between characters. The series is a landmark of the genre.
2. Trinity Seven (2014)
- Streaming Availability: Crunchyroll
- Rating: MAL: 7.1
- Episodes: 12
- Studio: Seven Arcs
- Notable Staff: Based on the manga by Kenji Saito and Akinari Nao.
Plot Summary: Arata Kasuga, a boy whose cousin disappears in a magical incident, enrolls in a magic academy to find her. He meets seven powerful female mages, each representing one of the seven deadly sins.
Similarities to The Testament of Sister New Devil: Both are about a male protagonist who forms bonds with powerful female characters and must navigate a world of magic and supernatural threats. The focus is on the harem relationships and the blend of action, comedy, and romance. The series is a fun, action-packed fantasy.
3. Date A Live (2013)
- Streaming Availability: Crunchyroll, Funimation
- Rating: MAL: 7.2
- Episodes: 12 (Season 1)
- Studio: AIC Plus+
- Notable Staff: Based on the light novel series by Koushi Tachibana.
Plot Summary: Shido Itsuka must date and seal the powers of “Spirits,” mysterious beings who cause spatial quakes. He must win their hearts to save the world.
Similarities to The Testament of Sister New Devil: Both are about a male protagonist who must form intimate bonds with powerful female characters to achieve his goals. The focus is on the blend of action, comedy, and romance, with a power system tied to the relationships between characters.
4. Campione! (2012)
- Streaming Availability: Crunchyroll
- Rating: MAL: 6.8
- Episodes: 13
- Studio: Diomedéa
- Notable Staff: Based on the light novel series by Jou Taketsuki.
Plot Summary: Godou Kusanagi, an ordinary high school student, kills a god and becomes a “Campione,” a god-slayer with immense power. He must navigate the world of gods and magic.
Similarities to The Testament of Sister New Devil: Both are about a male protagonist who gains immense power through an unexpected event and is pursued by powerful female characters. The focus is on the harem relationships and the blend of action, comedy, and romance.
5. Aesthetica of a Rogue Hero (2012)
- Streaming Availability: Crunchyroll, Funimation
- Rating: MAL: 6.7
- Episodes: 12
- Studio: Arms
- Notable Staff: Based on the light novel series by Tetsuto Uesu.
Plot Summary: Akatsuki Ousawa, a hero who defeated a demon king, returns to Earth with the demon king’s daughter. He enrolls in a school for those who have returned from other worlds.
Similarities to The Testament of Sister New Devil: Both are about a male protagonist who is incredibly skilled but underestimated, and is surrounded by powerful female characters. The focus is on the harem relationships and the blend of action, comedy, and ecchi elements.
6. Freezing (2011)
- Streaming Availability: Crunchyroll, Funimation
- Rating: MAL: 6.7
- Episodes: 12 (Season 1)
- Studio: A.C.G.T.
- Notable Staff: Based on the manga by Dall-Young Lim and Kwang-Hyun Kim.
Plot Summary: In a future where Earth is invaded, genetically modified girls called “Pandora” fight alongside male partners called “Limiters.” Kazuya Aoi is paired with Satellizer el Bridget.
Similarities to The Testament of Sister New Devil: Both feature a male protagonist who forms a bond with a powerful female fighter, with a power system tied to their partnership. The focus is on the blend of action, romance, and ecchi elements.
7. Sekirei (2008)
- Streaming Availability: Crunchyroll, Funimation
- Rating: MAL: 7.1
- Episodes: 12 (Season 1)
- Studio: Seven Arcs
- Notable Staff: Based on the manga by Sakurako Gokurakuin.
Plot Summary: Minato Sahashi, a failed college student, becomes involved in the “Sekirei Plan,” a competition where beautiful women with supernatural powers fight for supremacy. He becomes the “Ashikabi” of several Sekirei.
Similarities to The Testament of Sister New Devil: Both are about a male protagonist who forms intimate bonds with powerful female characters, with a power system tied to those bonds. The focus is on the blend of action, comedy, and romance.
8. Rosario + Vampire (2008)
- Streaming Availability: Crunchyroll, Funimation
- Rating: MAL: 6.7
- Episodes: 13 (Season 1)
- Studio: Gonzo
- Notable Staff: Based on the manga by Akihisa Ikeda.
Plot Summary: Tsukune Aono, an ordinary human, accidentally enrolls in a school for monsters. He must hide his humanity while navigating his relationships with the female students.
Similarities to The Testament of Sister New Devil: Both are about a male protagonist who is surrounded by powerful supernatural women and must navigate the complexities of his relationships. The focus is on the blend of action, comedy, and romance.
9. To Love-Ru (2008)
- Streaming Availability: Crunchyroll, Hulu
- Rating: MAL: 7.0
- Episodes: 26 (Season 1)
- Studio: Xebec
- Notable Staff: Based on the manga by Saki Hasemi and Kentaro Yabuki.
Plot Summary: Rito Yuuki, a shy high school student, is accidentally engaged to Lala Satalin Deviluke, a princess from an alien planet. His life becomes a chaotic mix of alien encounters and romantic misunderstandings.
Similarities to The Testament of Sister New Devil: Both are ecchi harem comedies about a male protagonist whose life is disrupted by a powerful, otherworldly girl. The focus is on the blend of comedy, romance, and supernatural elements.
10. Demon King Daimao (2010)
- Streaming Availability: Crunchyroll
- Rating: MAL: 6.6
- Episodes: 12
- Studio: Artland
- Notable Staff: Based on the light novel series by Shoutarou Mizuki.
Plot Summary: Akuto Sai, a young man who dreams of becoming a great priest, is instead prophesied to become the Demon King. He must navigate his new identity while dealing with the girls who are drawn to him.
Similarities to The Testament of Sister New Devil: Both are about a male protagonist who discovers he has a dark destiny and is surrounded by powerful female characters. The focus is on the blend of action, comedy, and romance.
11. So, I Can’t Play H! (2012)
- Streaming Availability: Crunchyroll
- Rating: MAL: 6.5
- Episodes: 12
- Studio: feel.
- Notable Staff: Based on the light novel series by Pan Tachibana.
Plot Summary: Ryosuke Kaga, a perverted high school student, makes a contract with Lisara Restall, a beautiful shinigami who needs his energy to survive. They must work together to fight against supernatural threats.
Similarities to The Testament of Sister New Devil: Both are ecchi action series about a male protagonist who forms a contract with a powerful female character, with a power system tied to their bond. The focus is on the blend of action, comedy, and romance.
12. High School DxD BorN (2015)
- Streaming Availability: Crunchyroll, Funimation
- Rating: MAL: 7.2
- Episodes: 12 (Season 3)
- Studio: TNK
- Notable Staff: Based on the light novel series by Ichiei Ishibumi.
Plot Summary: The third season of High School DxD, continuing the story of Issei Hyoudou as he fights in supernatural battles and navigates his relationships with the women around him.
Similarities to The Testament of Sister New Devil: As a continuation of High School DxD, this season shares the same themes of ecchi action, harem romance, and supernatural battles. It is underrated because later seasons are often overlooked, but it provides essential character development.
13. The Qwaser of Stigmata (2010)
- Streaming Availability: Not currently available on major platforms.
- Rating: MAL: 6.4
- Episodes: 24 (Season 1)
- Studio: Hoods Entertainment
- Notable Staff: Based on the manga by Hiroyuki Yoshino.
Plot Summary: Alexander “Sasha” Nikolaevich Hell, a Qwaser who can manipulate iron, is sent to a Japanese academy to investigate a religious artifact. He must form bonds with the students to survive.
Similarities to The Testament of Sister New Devil: Both are ecchi action series with a power system tied to intimate acts and the bonds between characters. The focus is on the blend of action, comedy, and romance.
14. Strike the Blood (2013)
- Streaming Availability: Crunchyroll, Funimation
- Rating: MAL: 7.1
- Episodes: 24 (Season 1)
- Studio: Silver Link, Connect
- Notable Staff: Based on the light novel series by Gakuto Mikumo.
Plot Summary: Kojou Akatsuki, an ordinary high school student, becomes the “Fourth Progenitor,” a powerful vampire. He must protect the city while dealing with the girls who are drawn to him.
Similarities to The Testament of Sister New Devil: Both are about a male protagonist who gains supernatural powers and is surrounded by powerful female characters. The focus is on the blend of action, comedy, and romance.
15. Aesthetica of a Rogue Hero: Hagure Yuusha no Aesthetica (2012)
- Streaming Availability: Crunchyroll, Funimation
- Rating: MAL: 6.7
- Episodes: 12
- Studio: Arms
- Notable Staff: Based on the light novel series by Tetsuto Uesu.
Plot Summary: Akatsuki Ousawa, a hero who defeated a demon king, returns to Earth with the demon king’s daughter. He enrolls in a school for those who have returned from other worlds.
Similarities to The Testament of Sister New Devil: Both are about a male protagonist who is incredibly skilled but underestimated, and is surrounded by powerful female characters. The focus is on the harem relationships and the blend of action, comedy, and ecchi elements.
Why These Anime Work for The Testament of Sister New Devil Fans
Fans of The Testament of Sister New Devil are drawn to stories that blend ecchi action, harem romance, and supernatural drama. They appreciate a narrative that focuses on a male protagonist who forms intimate bonds with powerful female characters, and they are invested in the relationships and the comedic and dramatic situations that arise. They are not looking for complex philosophical narratives, but for fun, entertaining stories that make them laugh and feel.
The anime listed above all share this fundamental DNA:
- The Intimate Bond: Whether it is the master-servant contract of The Testament of Sister New Devil, the Ashikabi-Sekirei bond of Sekirei, or the devil-servant relationship of High School DxD, these series understand that the bond between the protagonist and his companions is central to unlocking true strength. The focus is on the trust, loyalty, and intimacy that develops between them.
- The Underestimated Protagonist: The protagonists are often initially dismissed or underestimated, but they prove their worth through determination and the strength of their bonds. Their journey is one of earning respect and finding their place.
- Subversion of the Harem Genre: These series use the framework of the harem genre to explore deeper themes of family, loyalty, and sacrifice. They understand that the most compelling stories are not just about choosing a partner, but about the bonds that form along the way.
These 15 anime, like The Testament of Sister New Devil, are not afraid to be bold. They are underrated gems that offer a fun, action-packed, and emotionally resonant experience for viewers who are looking for stories about the power of bonds, the thrill of battle, and the beauty of love.
