Thanks for playing! Very good points you've made! Absolutely agree that visual indicators should be clearer and should space out more to reduce clutter.
As for choosing Miko and Aki, it was mainly because they are the members that are the most involved (from my knowledge) with tsunomaki janken during that era.
For Aki, Watame would sometimes have Mukirose take over her Janken segment. Her segment would usually involve a "pose", and any hand viewers play would be a losing hand (this couldnt be implemented for obvious reason, so I went with the compromise of "posing with her")
As for Miko, her livestream would usually overlap with Watame's show during that time. Whenever it happens, she would livestream her "reaction" to it, and would play along during the Janken segment. Running joke is on her lose rate on these live, which is amazing honestly looking back.
https://www.youtube.com/watch?v=2Pd6E1v2JqI
Did try to make it more visually obvious by having a somewhat different skin tone (Miko's is darker than Watame's) and a differently drawn hand pose for each character. Maybe they could also have a striking colored outline to increase the visual clarity.
Thanks for your valuable feedback!