I love math. Just after the high school entrance ceremony, I meet a beautiful girl: Milka. Milka is a mathematical genius. She gives me many math problems, she shows me many elegant solutions. Milka and I spend a long time by discussing math in the school library.... more>>

One year later, I meet another mathematical girl: Tetra. Tetra is one year younger than me, and asks me to teach her math. While I teach her, she begins to understand math and to love its elegance gradually.

The second series is about Pythagoras Theorem, Elementary Number Theory, Group, Ring, Field, and Fermat's Last Theorem. <<less

Tomoki, a high school student lived with his older sister. What happens when a normal boy has to put up with his sadistic but popular... more>> sister? <<less

Demon Queen Abyss is worried… She's not able to defeat the Hero, considered the mortal enemy of the demons. This Hero is still an inexperienced... more>> young man—he should be easy to defeat! … However, the problem is that he, not knowing Abyss's true identity, considers her his “Master” and has become very fond of her…!? <<less