There is so much cuteness in this thread that it's unreal
It's seriously difficult for me to decide who I'd pick. There are a lot of contenders. Myao, Rabutan and Mayuyu to me are a really fun kind of imouto cause they all kinda have this 'bad girl' vibe to them. Like how they'd be all nice one minute and suddenly switch. Actually, come to think of it, Rabutan and Mayuyu are queens of Tsundere aren't they?
And then there are the girls that just seem really sweet like Jurina, Suu-chan or Miorin. They all just seem gentle and kind.
And thats just thinking off the top of my head really. I'd probably come up with more girls I really like as imouto if I thought about it longer.
But my number one would have to be non. Once I first saw her in a vid (Can't actually remember what the first vid was) that was it. I was totally won over. She's my number one imouto