Kunoichi no Ichi! no Ni

Kunoichi no Ichi! no Ni is a Manga/Manhwa/Manhua in (English/Raw) language, SUGGESTIVE series, english chapters have been translated and you can read them here. You are reading Kunoichi no Ichi! no Ni chapters on VipToon, fastest updating comic site. The Summary is

A high school student Ichi who visited a ninja residence on a school excursion was caught in a strange structure during the tour and time slipped to the ninja world. Along with his friends, Ichi who got the “Ninpocho”, a key to return to the present age, returns safely to the present age. However, suddenly an awakening appears in front of Ichi who lives a peaceful life ...!?