Natsu no Rakugaki

Hikaru, a city boy raised in Tokyo, spends his every summer in the countryside with his grandmother ever since he was little. There is a girl in this town called Rin Natsukawa and she has been forcing him to play Kendo with her, or in other words, bullying him every time he comes over. One time while they were fighting Kendo, one promise was made between these two, and he has been practicing hard to fulfill that promise.