Mika Seguchi

Mika Seguchi (瀬口 美華 Seguchi Mika) is a main character from the popular anime and manga series, Gravitation.

Basic information
Eiri's older sister and Tohma's wife. She's beautiful, yet cold. She looks quite a bit like Eiri except with longer hair and makeup. In book one, she wanted to make Eiri see his dying father, bribing Shuichi with her own husband (Tohma). Later in the manga series we find out she and Tohma are going to have a child

Eiri Yuki
Mika is Tohma Seguchi's wife and Eiri's sister. She cares a lot about Eiri and would give almost anything for him. She supports and doesn't support Eiri's relationship with Shuichi. More than anything she tries to be real with both men, letting them know the complications their relationship would cause on the world around them. But she does seem to want them to be happy, mostly because Shuichi genuinely makes Eiri happy. She doesn't speak about Tatsuha, her youngest brother, who happens to be a monk, but more about Eiri.

Shuichi Shindou
Extremely disliking Eiri Yuki and Shuichi's relationship together, (seen in the anime), Mika often tells Shuichi that he doesn't know everything about Eiri Yuki like she does. They actually have a mini argument in Eiri's apartment about mini embarrassing things Eiri does. The most common place Shuichi and Mika is over dinner.

Tohma Seguchi
Mika and Tohma were married three years before the series starts. When Tohma states that he "loves him [Eiri] more than anything else in the world", it later becomes evident that not only does this include Mika, but that she also knows about it and accepts it with little trouble. When Eiri in volume eight misinterprets her suggestion that he humor Tohma's smothering as an encouragement to having an affair with him, she tells him that Tohma's love for him is merely "motherly". Yet, when she and Tohma discuss Eiri in volume ten, she wonders why Tohma isn't off protecting his "precious Eiri" from his "hated rival, Shuichi". When Tohma apologize and promise to focus more on her and their unborn child, she also asks him to protect her brother as well.

Even though their exact feelings for each other remain unstated, it is clear that Mika is one of the very few people truly close to Tohma Seguchi.