Shiki Tsukai

On the day he turns fourteen, Akira discovers his destiny: He’s a shiki tsukai, a warrior with the magical power to control the seasons. He also meets the beautiful Koyomi, another warrior, who is sworn to protect him. For there are evil forces intent on destroying Akira–and the entire universe!

(Source: Del Rey)

Shiki Tsukai had eight volumes published in English by Del Rey from August 28, 2007 to September 28, 2010, with volumes 7 and 8 combined in one volume.