Ani-Imo, Vol. 2 - Haruko Kurumatani

When elder brother Youta and kid sister Hikaru get into an accident that switches their bodies, Hikaru (in her brother''s body) changes into a fiendish sadist, and Youta (in his sister''s body) finds himself her "girlfriend." Thrust into a bizarre reality where he''s now taking orders from his own body, will Youta ever get himself out of this pinch and back where he belongs?!