Set six years prior to the events of Barakamon, detailing the life of Seishuu Handa as a high school student—and a very interesting life it is.

In Handa-kun, Seishuu Handa is admired by his peers as a calligraphy genius and given the utmost respect, but Handa-kun himself is under the mistaken impression that the deference and attention he receives from the other students is actually bullying. Handa just wants to live a quiet life, but hilarity ensues as one character after another challenges his position as the school idol, and somehow comes away as a fan all while Handa is horrified and clueless.