This chapter is about design right? So I’ll give my 2 cents.
FREAKING FISH KNEES! Why? Mermaids are monster girls, they’re otherworldly and somewhat inhuman. Their lower half is literally that of a fish, and yet so many artists just draw the tail like fused legs with a big bend in the middle...
A very fun series, I will be sad to see it go. But this is why, dear friends, harems are bad and lame. Just pick one girl and stick with her.
In this case, the choice is obvious.