The translation on page 29 is a little weird. I went back and looked at the original and it basically emphasizes scrubbing it "out" versus washing in general.
Here, they try to compare "scrub" with "wash" which really doesn't capture the phrasing the aunt is using that's hinting at having cum dripping out of her.
Hopefully in part 2 Kaito recorded him with Yuki, shows it to Sota, and then fucks him in front of her. Turns out he just wanted to be with his two great loves this whole time.
Here, they try to compare "scrub" with "wash" which really doesn't capture the phrasing the aunt is using that's hinting at having cum dripping out of her.
Hopefully in part 2 Kaito recorded him with Yuki, shows it to Sota, and then fucks him in front of her. Turns out he just wanted to be with his two great loves this whole time.