Sonny Astrobald est un jeune garçon turbulant et macho. Petit par la taille mais grand par le coeur, il n'hésite pas à voler au secours des gens qui solicitent son aide.

Arrivé comme pensionnaire dans son nouveau collège il fait la connaissance de Lydia qui tombe immédiatement amoureuse de lui, malgré qu'elle soit beaucoup plus grande que Sonny.

Entre les cours de maths du terrible Monsieur Théorème et les diverses excursions entre le dortoir des filles et celui des garçons, comment Sonny et Lydia vont-ils vivre leurs tendres années ?

这部动画以阳光学园为背景舞台，讲述了因为个子矮而讨厌女生的硬派中学生青叶春助和对他一见钟情昵称为“艾露”的大个子同班同学朝丘夏美之间又打又闹的青春恋爱故事。

Shunsuke Aoba has just transferred to a new school and can’t wait to attend. Excitedly, he sprints to the school but, upon arrival, finds that no one is there. Unfortunately, Shunsuke didn’t know that his first day was a holiday, of all things. However, it seems that he is not the only one on campus. As he is about to eat his lunch, he meets a student named Natsumi. Shunsuke gives her some of his food, and the two strike up a conversation. Natsumi was born as a so-called SL girl, a particularly tall girl. She herself accepts her specialness but is rejected by many of her classmates. How will Shunsuke react to this? Will their initial friendship continue?

La madre di Shunsuke Aoba (Sanyo Aoba/Alex Fox, in Italia) gestisce un negozio di intimo femminile ed il ragazzo si ritrova quindi sempre circondato da donne. Per cambiare aria decide di iscriversi al Sun College, un liceo che crede sia solamente maschile, ma è costretto ben presto a ricredersi, perché anche lì ci sono delle studentesse, in particolare Natsumi Asaoka (Lory Asaoka/Lisa) che si innamora di lui. Shunsuke pur trattandola con freddezza finirà col ricambiarla, e insieme formeranno una delle coppie più strane, soprannominata S (lui, da small, piccolo) e L (lei, da large, grande).