Shinobi Undercove is a Manga/Manhwa/Manhua in english language, Action series, english chapters have been translated and you can read them here. You are reading chapters on www.mgeko.cc fastest updating comic site. The Summary is

Even in modern Japan, ninja still hide in the shadows. Young ninja Yodaka has received his mission--protect high school student Aoi at all cost. But can a ninja survive the wild world of high school while also fulfilling his mission?