Saijo is a university student with a special ability. Whenever he sees a woman in love, he can see bright sparkles around that woman. Kitashiro is Saijo’s childhood friend. Kitashiro tells Saijo that she has feelings for him, but Saijo tells her he doesn't see any sparkles around her. This makes her frustrated. At that time, their school mate Yadorigi approaches Saijo, because she believes Saijo is Kitashiro’s boyfriend. Yadorigi has a bad habit of approaching guys who are already in a relationship and trying to seduce him. Meanwhile, Saijo happens to meet Shinonome. They exchange a diary with writings about what love is. Kitashiro attempts to disrupt the budding relationship between Saijo and Shinonome. Adapted from the manga series "Koi wa Hikari" (恋は光) by Akieda.