Hakuya's younger sister, who somehow manages to enroll in Kobeni's class. She often tries to vocalize that she isn't a child, but her honest feelings over her likes and dislikes are often read easily by the others. She is quite fearful of Benio but is easily swayed by sweet things.

Not every girl gets what she wants on her 16th birthday, but Kobeni's gift is something she never saw coming: an arranged marriage! Thanks to her late grandfather, Kobeni's been engaged to a total stranger since childhood, and even though she's supposedly met him she doesn't remember a single thing about him. Even weirder is that both her Mom and creepily over-doting sister, Benio, seem completely unsurprised when the groom-to-be, Hakuya, and his younger sister, Mashiro, show up on the family's doorstep to move in with them!<br>
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But it's not until they start attending Kobeni's school that things take an even stranger turn after she starts to pick up some very... unusual vibes from her potential future family. From Mashiro's obsession with aliens and UMAs (Unidentified Mysterious Animals) to Hakuya's disconcerting lack of emotion, there's something very off about them that Kobeni can't quite put her finger on. What has her grandfather gotten her into, and how does this relate to the strange gap in Kobeni's memory?<br>
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(Source: Sentai Filmworks)

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__Non-Anime Roles:__
- Arco in "Marco & The Galaxy Dragon" (VG) (Japanese)

The anime follows the daily life of an earnest, hardworking office lady named Kaoru and her otaku husband, who is totally immersed in a certain huge net bulletin board system.

 The manga is about an ordinary girl Yonomi Kobeni who suddenly heard that she is betrothed to a guy Mitsumine Hakuya who is the same age as her. Somehow Hakuya moved in from countryside and started to live with her, bringing his younger sister who is still a primary school student with him. Added Kobeni's elder sister who already lives with Kobeni and is 2 year older, the story revolves around these 4 people and their identities as "couples" and "sisters-in-law."

OVA Bundled with the first volume of the BD/DVD.

Unaired episode included in the special edition of the 5th manga volume.

Mashiro Mitsumine