Summary from Bushido Angel Adventures:
Shouta is constantly getting in fights, but despite that, he’s a nice guy. One day, while saving someone from some bullies, a weirdo samurai guy shows up and tells him he’s haunting him. Now Shouta must deal with this constant spiritual companion... and all the emotions that come with him!
It the 5th chapter in http://www.mangafox.com/manga/boku_no_shiru_anata_no_hanashi/