Saving Miia by ramming a boat in the middle of a large lake—with a swan pedal boat, to boot.
Kimihito shows his Badass credentials again by calling out Ren on her motives, stating everything about her that made him refuse letting Rachnera go with her. She didn't get the message, but that was still pretty admirable out of him. Rachnera was quite moved too, although she didn't show it until she got drunk on coffee.
Also, there was an accidental Take That to her as Kimihito had just come home from shopping and had brought something to drink for all the girls, and his gesturing during offering them the drinks was basically saying that "This guy can deal with half a dozen other girls than Rachnee on his own, and you're still convinced that you would make a great host to her?". Of course, she didn't notice that part, but the internet did, and Kimihito's popularity rose.
Chapter 27 had quite a lot. Luring Mama Miia into a refridgerated storage unit, withstanding the aphrodisiac she drugged him with by giving himself a cold shower and finally dragging two unconscious lamias to an onsen where they could recovernote For the record, an 8 meter anaconda (Miia's official length) is estimated to weigh about 200 kilos (or 440 pounds) and he dragged both of them.
Suu saves a little girl from a car by absorbing her and then taking the impact herself.
Meron showing what's she's REALLY capable of in the water in chapter 17. Miia gets one as well for being able to keep up with her during the race (at least until their respective weaknesses kicked in).
Chapter 20 has the Kaiju Girl Fight. It must be seen to be believed.