|Eye Color||Dark Blue|
|Relative(s)||Minatsu Shiina (big sister)|
|Position||Treasurer of Student Council|
|Light Novel Debut||Volume 1|
|Anime Debut||Episode 1|
|Seiyu|| Yuki Horinaka (first season)|
Iori Nomizu (second season)
Mafuyu Shiina is a primary character in Seitokai no Ichizon.
Mafuyu is the Student Council Treasurer. She is Minatsu's sister and the only freshman in the Council. She is a swaying bishōjo, and is afraid of males (though she lightens up to Ken). When it comes to boys' love/ yaoi, Mafuyu can actually be just as perverted, if not worse, than Ken. She's addicted to video games, and spends much of her free time playing with a handheld game console that resembles a pink PlayStation Portable. Like the season she represents, she's extremely passive and keeps a lot to herself, but she will show her real self and her real feelings if she feels comfortable.
Mafuyu and Ken Sugisaki met in the winter (真冬 = winter) chatting online with him as Yuki (with Ken as Key) and even having a more spirited personality online. Ken fell asleep once in the snow and, despite her fear of men, took him out of the freezing cold. Their meeting showed him a clear understanding about what strength really is.
Despite her shy personality (or based on Ken's logic, because she's shy) she confesses her love to Ken, although she says she just wanted to share her feelings with him rather than start a relationship, because she loves the Student Council's atmosphere most of all, implying that even when she loves him she doesn't want to change how things are at the moment.
Ken thought her to be "the easiest character to see the ending" but later turns out to be the most feared one by some reason, even when compared to Chizuru, particularly the fact that she's a fujoshi, and that she fantasizes pairing Ken romantically with a boy named Yoshiki Nakameguro (who turns out to be an actual person).