Idk about the CG bc I haven't done Shiba's route yet, but as for the chibi gallery the first one is the 69 position, the second one is butt groping, and the third one is the other guy licking your finger. For the first chibi, I think the guy you're romancing has to be the dom top bc he'll be the one to initiate it. In my case, I had to make Haato keep licking his partner's penis in different positions in every visit to the love hotel. It takes a few dates before (in my case) Hikaru initiated the position. For the 2nd, you just have to keep groping the other guy's butt. For the last one, Haato's partner should be a bottom. If he prefers being a bottom, he'll eventually lick Haato's fingers. From my playthrough, I just kept making Haato lick his partner's fingers/asshole and eventually it happened.