From MangaHelpers:

Mikado Shuuji is just an ordinary guy, but he has a very unusual knife that he uses for cooking. It's actually a famous short sword that marks its owner as the head of the ninjas, and now there are hot ninja girls coming after him to take it back. Hinamori Botan is one of those hot ninja girls, but her efforts to attack Shuuji mostly end up inadvertently stripping her. After she concludes that she does not want to steal the sword and kill Shuuji, she ends up deciding to serve him as a ninja instead. Now she must protect him from the other ninja that come to claim his sword and his life!

After an accident our protagonist Amagami Kouichi becomes involved with Itanami-san a well known beauty of his school and secretly a vampire.

The master spy codenamed has spent his days on undercover missions, all for the dream of a better world. But one day, he receives a particularly difficult new order from command. For his mission, he must form a temporary family and start a new life?! A Spy/Action/Comedy about a one-of-a-kind family!

(Source: Manga PLUS)