Okay that's just wrong. I help them and they steal from me (I now see how the brothers are related)
To get the Koi you need to lose the second game and fallow this dialog path talk 1, talk 2 (answer: accept), Discus hypnosis (answer: It sounds like a pleasant experience), Hypnosis Lesson (answer: hypnotize me) if your going for the female version you ether need to be a princess or a maid. you can't be a spy