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