A lot of them are
very grindy, you can get all of them after doing:
- for one, level 100
- defeat a total of 1000 enemies
- defeat 20 of each normal mob
- defeat 5 of each boss
- climax in sex 50 times with each type of enemy (boss included)
- birth 100 grown children of each type of enemy's offspring (boss included)
- vaginal birth experience 1000
- breast birth experience 1000
- drink 1000 bottles of breast milk
- drink 1000 bottles of semen
- create 1000 bottles of breast milk
- get into the nursery (the stage 3 boss defeat scene) multiple times
I used to have a save like that in my old laptop, and it's genuinely annoyingly grindy, might as well just enjoy the experience while going through all that.
Fastest way to grind to lv100 is to keep respawning and defeating the titfucking hornet group multiple times in Naedoko difficulty, on 100% achivement hunting this one should be the last to go for after doing literally everything else. Ice magic is their weakness.
Doing the birthing goals early is fastest because you die and respawn easier, and for slime-type enemies you can just leave at least one in her while you reload every room, they keep spawning more slimes inside her per room reload. Waiting for 100 birthing animations per enemy, is well, an experience.