When a broke, overworked, and hopelessly single university student named Masato witnesses a dog being abused by some punk kids on the street, he does what any decent human being would do and comes to the poor creature's rescue. Later, a mysterious young man claiming to be that same dog shows up at his doorstep in hopes of repaying his life debt – which would be all fine and dandy if his new friend's knowledge of human culture wasn't seriously warped by Masato's rather explicit smartphone browser history. 361c5w

Official English:
Irodori Comics, FAKKU