Aika is a second-year student who is in the same class as Asia and the Perverted Trio. She wears spectacles and like Motohama, she has the ability to calculate a male's "manhood" size just by looking. A good friend of Asia, she likes to tease the latter about her crush on Issei. One of her most well-known traits is her habit of giving lewd advice to Asia, such as telling her about "skinship" and encouraging her to try it with Issei in the bathroom and warning her not to dilly-dally in making a move on Issei before the other girls could get him.

(Source: Highschool DxD Wiki)