Nishikicho Park is a lovely place to take a breather. Have a picnic, amble around the grounds or just lie on the cool grass and shut your eyes for a while.
To explore this recreation and green space, you'll need to find your way to Aoba Ward. You'll find loads of other worthwhile attractions in this area, including Tohoku Gakuin University Tsuchitoi Campus, Sendai Anpanman Children's Museum & Mall, and Sendai International Center.