Silence

(1-3) Rebirth
Zenji finds out he has a terminal illness called VEB and has to retire from his SIS job. As he walks home, depressed, he runs into a boy who asks him to protect him in exchange for money.

(4-6) Bet, Bed-Millie's- & Bed-Theo's-
Theo has one-sided feelings towards Millie who is heart broken over Zenji taking a lover. Theo breaks into Millie's apartment and nurses him back to health after he forgot to eat causing him to collapse from working too much.

(7-10) Silence
Luca Angeli was born without a voice, but as he grew to have a beautiful features, his parents sold him to the mafia, where he has been living as a (sex) toy. One day, his cruel owners were taken down by Shion, a mafia hitman with mysterious powers, and he was freed. However, with nowhere to go, Luca could do nothing bur remain where he was, thinking of his stoic-looking, taciturn savior...

(Source: Baka Updates)