Days before the cheating....

Days before Makoto and Sekai decided to do what they did, things started off with a phone conversation between them.

Sekai: Hey Makoto. So what did you want to talk about?

Makoto: I wanted to talk to you about.....Kotonoha?

This raised Sekai's curiosity a bit.

Sekai: Okay? What's the problem?

Makoto: Her. She's the problem. I thought dating Kotonoha would be fun but it's....honestly just tiring. Maybe even boring. And I know your boyfriend's partly to blame for it.

This made Sekai angry at Makoto since she knew Flukey was only trying to help.

Sekai: Hey don't pin the blame on Flukey! He's just trying to help like I am! Not our fault you can't learn how to treat a girl right!

Makoto, upon realizing his mistake, immediately defused the tension.

Makoto: S-Sorry sorry! I didn't mean it like that. I was just trying to say that Flukey's teaching Kotonoha things that might hinder our relationship. Plus, you know he doesn't like me.

(For good reason)

Sekai: I know but he wouldn't do anything to mess up you and Kotonoha's relationship. He's better than that.

Makoto: Yeesh, you talk about him like's he's the perfect boyfriend.

Sekai: He may not be perfect but he's better than most.

Makoto: Well if that's the case then you and him must've already had sex then?

Sekai: *Blushes* Makoto!

Makoto: What I'm just asking a question? Unless you haven't done it with him yet.

Sekai: Tsk. If you must know, we haven't had sex yet. He says he's willing to wait until I'm ready.

Makoto: Oh.

After that awkward moment, the conversation gradually moved normally before both parties ended the call.

On the day of Sekai's sin, it was another normal school day and at the end of it, Makoto requested another lesson with Sekai on the roof.

Kotonoha saw no issue with this and Flukey trusted Sekai enough to let her go, not knowing that he would come to regret this decision later.

Now on the roof, Sekai and Makoto once again practiced and once again it proved fruitless.

At this point Sekai was considering giving up on Makoto completely and just leaving him to wallow but Makoto wasn't willing to give up.

In fact, he brought up the topic of kissing and sex again.

Sekai, repulsed by this, tried to cut things short but Makoto wasn't having it and pressed his lips to Sekai's. At first she resisted but slowly gave in, having awakened her deep-rooted love for Makoto long before Flukey came into the scene.

As the deed was being done, unbeknownst to them was that Kotonoha caught them in the act and Flukey was unaware of what was happening.

But like all sinful secrets, it's bound to be revealed sooner or later.