I would love this too to be implement as It'll sure hell save the time of having to edit saves putting custom chars I've made. The best part is that Strive already has the means to do this with you being able to customize you first girl which leaves the only issue being how to store the character data (which can probably be done like save same data) and how to how spawn characters into the world.
This can also give Sebastian added utility beyond being a reliable but pricey source of rare races, aside from just picking the rare of the girl you want, you can have him find one with specific hair and color, gender and body, and maybe traits and stats. To balance this, there's an added price multiplier for each added specification and will also cost mansion upgrade points. I mean, after getting every upgrade, mansion points will become meaningless.
And on that note, why not make those points be used for different other things and give them a new name like Influence or something. Aside from what I suggested with Sebastian, you'll can also need to pay in influence to buy spells from the guild (which makes sense honestly) and influence also gives you access to buying higher quality slaves at the Slaver guilds.
Heck, why not give the player the option to make our own custom requests to the guild, it functions similar to what I suggested for Sebastian but the race pool is limited what the various guilds normally sell and there is no added multiplier to specifications hence it's cheaper to buy from them than Sebastian.
- Humans, Elves and Tauruses in Wimborn
- Orcs, goblin and centaurs in Gorn
- Beastkin and Halfkin in Frostford
- Umbra provides us with the "exotic races" like Demons and Seraphs
Well, this post ended up being bigger than what I originally intended. (Basically being a me too post) XD