Throughout his high school years, Shouichi Kamita struggles with the common strains of university admission tests and the uncertainties of his future. Moreover, Shouichi experiences the enigmatic sensation of love that can affect anyone, regardless of age. As a teenager, Shouichi becomes enamored with three potential love interests, who he imagines a future with: Hikari Tsuneki, an animated girl who enjoys teasing him but also has a soft side; Tooru Miyamae, an accomplished gamer who has difficulties communicating; and Kyouko Touno, his childhood friend who loves shoujo manga and has some childish tendencies. Seiren follows Shouichi as he embarks on three distinct storylines navigating his relationships with these three girls, revealing the transformation of their initial attraction into a truly magnificent love.