Found this in the comments, hope it helps to fill in the gaps! :)
"KarlaMarx March 5, 2018 8:15 pm
I actually ended up buying a hardcopy of the Japanese manga because I really wanted to know what happened in the missing chapter as well. Basically, Himuro takes Reiichirou to a masquarade where they dance together and suddenly a black out occurs in the middle which is when the two get separated. In this time, Reiichirou is kidnapped by a masked Arisawa who gropes Reiichirou in the dark. Reiichirou manages to escape and finds Himuro who becomes concerned with seeing Reiichirou's disheveled clothes. Himuro hugs Reiichirou and tells him he'll help him forget his trauma thus, the beginning of the last chapter (which is chapter 5 on here). Hope that helps! (=・ω・=) ALSO, the mark that Reiichirou has on his neck which Himuro bites during that sex scene is the mark that Arisawa left during his and Reiichirou's encounter in the dark."
thank you alot :x
yo until someone buys the manga and (kindly) put pics of the missing chapter online we will NEVER know..