I wouldn't say quit, but he's quitting a utaite. Due to him moving back to his hometown in Akita. He says its very difficult for him to do his utaite activities in there. Possibly one of the hardest decisions he had to make, but hopefully we can all respect his decision. But he's not quitting entirely, he says he might come back, so consider it as a hiatus while he's just moving. Maybe through that time he can release a couple covers but at the time he won't be doing any utaite activity. 

(and here'sa translated blog entry that was posted onto tumblr that Kanseru wrote as to why he's leaving) hopefully this helped

I don't think he will quit either. He probably needs to take a break whilst he moves back to Akita. He tweeted earlier today about wanting to do more song covers in english, so it will most likely just be a small break. ^•^