It looked like Kodoka was relieved to learn that Yukimura was a girl all along, since it validated his sexual orientation. So all of those "confused feelings" and arousals he had around her were perfectly normal and weren't born out of some dormant homo desires. And it's all thanks to the poopy Maria peeking at their package!
Honestly, I would have died if the actual question Maria asked Yukimura was: "Why is your wee-wee SO MUCH BIGGER than Oni-chans??? It's
really BIG!!!"
I would've just killed myself if I were Kodoka. Or hope that she was futa...