Oh, did that last Mahir scene genuinely sneak up on you? That was the intent, but I feel like most people just miss it and then go back and get it with the walkthrough when they're trying to 100% the gallery. Very happy if you managed to landmine yourself with it as intended :D.
Sadly I wasn't achieved that scene myself but with the help of the scene guides. I was like normally doing slut run and pure run like the Chapter 1 then come to see more contents and saw that last Mahir scene.
The funny thing is I yeet-ed myself 3 times with the Adder's stuff just to get in the slut mode asap. Mahir must be disappointed that he would yap "Huh? Bunbun isn't you just won our battle a couple of minutes ago?" :C