From Yaoi Is Life:

Seina, who's a tattoo artist is entrusted to do a tattoo with a very difficult design by a peculiar customer named Jin. He is confused, but happy his skills are being recognized. Surprisingly, Jin is always meddling in his affairs, and it makes him feel close to him. For Seina, who left home and has a bad relationship with his own brother, Jin is like a big brother he can look up to and put his trust on. But Seina finds out that Jin is actually his brother's friend, and only came to him on his brother's request...