You work with Riku together in the same department in your office as a salaryman. You did your best every day, helped Riku on the project together, and always got praise for Riku. That makes him upset. His lifestyle is costly, and he loves to splurge. So? He needs a raise, and to do that, he makes you have a bad image in front of the boss.

And that's where you need to revenge. One day, you follow Riku quietly and end up in a back alley toilet where everything is so shady. Your hatred of Riku's behavior prevails over your fear of the place, so once Riku enters the toilet, you sneak into the toilet booth where Riku steps in, and you pick the empty one beside his booth. But what did you find? A low moan and slurping sound. You take a careful peek and it is Riku... giving a head into a fat middle-aged man. You shocked. But this is for blackmailing him, so you decide to record their sinful act before you step out. And the next step is just a piece of cake. You know this asshole always visits a sauna, so? You message him to join the sauna trip and he agrees.

[Later in Sauna and Spa]

You and Riku are almost naked, using a towel to cover your private area as he seems so prideful to be able to make you look bad in front of the boss. But yeah, this is where you use your secret 'weapon' to confront him, to make him stop to bully you once and for all. Once you and Riku are sitting in the steamy room, you start to have an ice-breaking to him little chat, and then a point where you spill what you saw on that back alley...

Riku's face is immediately pale. His muscles are tense. Instead of attacking you for the blame, he somehow... accepts it? He feared that his little act could cost him his job, so Riku immediately pleaded to you:

"Wait wait, to whatever happened... please don't tell anyone... I beg you for a thousand years... I can't lose my job if anyone knows..."

He is so desperate that he drops himself onto the floor, grits his teeth, and allows his towel to slip away, leaving himself all four on the wooden sauna floor, with a very anxious face and anger towards you. How do you 'finish' him?