Yokosu Inu, Mekuru Yoru summary:

The setting is a yakuza-run casino. Part-timer Kikuchi is a hoodlum and a dealer. He’s being punished for getting Shintani involved in an embezzlement scheme. The one who ordered the punishment is the boss’s "woman," Sudou. The order is "Rape Kikuchi on video." Shintani steadfastly refuses this arbitrary command, but with the promise of Sudou taking him in his mouth, he might see his way to raping a sobbing Kikuchi... Raise the curtain and jump into the middle of a messy, underworld, three-way relationship!