Good day. It happened so I murdered the Black Scorpion in Raikan, however, I would desperately wish to add him to my collection. But when I edit my save file I can't find **$raien1 variable there. May I have more specific instruction?

Do you not have a backup for an earlier save? You can download saves and keep the file on your computer anywhere. That's a good way to keep backup to points you want to restore.

But I didn't see 'Black Scorpion' under scripted random male NPCs list on the wiki, so he's probably just a randomized NPC with higher base stats. You probably aren't missing by killing instead of enslaving him if you are already doing save state editting as you can freely change character stats.