Douyara Aitsu no Ichiban wa Ore no you deshite

Everyone knows Natsuki Tachibana is handsome, has a great personality, and is popular with the ladies—including himself. His childhood friend Toshifumi Oda is right up the ranks with him, but Toshifumi consistently turns girls down by saying he's already in love with someone. Curious to know who it is, Natsuki challenges his circle of friends to a dare, and whoever loses has to ask him out. When he loses, he summons Toshifumi to the school roof to ask him out. But, when he starts to admit it's a joke, Toshifumi responds and says he loves him, too...!

(Source: Renta!)