Kawaii Obaka-kun

From Pink Cherry Blossom Scans:

A gaudy young man named Taiichi, captivated by big boobs, accidentally dented the high-class car of a Yakuza member. In order to pay for repair fees, he ends up having to make a post online, selling himself to prostitution. At the Love Hotel he was called out to, he was met with an unfashionable man with messy hair. However, this lame man told him, “I’ll give you money in exchange for your obedience.” At his wit’s end, Taiichi was prepared to lose his anal virginity, however----…

Also, the slapstick love comedy about a College student who took in a man with an amazing dragon tattoo on his back, and other short stories are compiled together.