Sirix's best friend, Loleus, reincarnated as a girl. Serizawa has known Keidai since 7th grade and was the first to learn about his past life. Keidai finds Serizawa trustworthy and often confides in her when something is on his mind. She has an apparent crush on Keidai, which happened before the beginning of the series, but says nothing, because she knows Keidai is still in love with Serena. She is very mischievous and likes to toy with people, especially Keidai. Serizawa is sought-out by some of the boys in the high-school division, but they all hold-back because everyone believes she and Keidai are a couple. She can be ignorant towards the most obvious things, much like Keidai, such as the fact that Yuuma has a crush on her. She is in Keidai's class.