It's easier in the game for female characters to have multiple orgasms than males, but males can have multiple orgasms with certain sex toys, certain techniques, or if they are especially horny.
https://argonvile.itch.io/monstermind/devlog/547945/monster-mind-sex-guide-puzzl...
There is a detailed sex guide available, although it goes really deep into the weeds and might kind of kill the magic if you would rather figure things out through experimentation! Heracross's instructions for the sex toy might be one to start with, since I think it is extremely difficult and tedious to deduce by playing the game normally
Thanks a lot! I hope one day I'll be able to play another of your games. Monster Mind has an unique charm, each character has their own character that goes beyond just being sex-related. I think more erotic games should be like this, it's great to feel some kind of emotional connection with the character.
Cheers~!