Natsuzora and Run

Second baseman Kaizu Chiaki is a normal senior high schooler who aims to reach the Koshien with his teammates and worries about his future career. One day, a new teacher arrives at his school. Her name is Takamine Touko. Crossing the boundaries between teacher and student, Chiaki and Touko find themselves gradually attracted to each other.

(Source: MangaHelpers)