Wait, she can rely on Ritsu? That's a new one.
Yes! Yes she can! This is part of the brilliance of MioRitsu and why I love the couple so much. They are so wonderful for each other.
(rambling fangirl rant)
Mio is a scaredy-cat. She wants to experience new things - she enjoys them once she's started them! - but she's too scared to take that first step. Ritsu knows this, and Ritsu is the one who can always coax her out of her comfort zone... often by dragging her along for the ride with her.
Once Mio is settled, she's the hard line that keeps everyone else in check. She's the one that complains about them not practicing as much as they should or getting distracted by this or that. It's particularly important that she keeps Ritsu from getting distracted by her next big idea, too.
Ritsu always helps Mio feel comfortable when she's out of her comfort zone. She acts like a total dork, gets a rise out of Mio and makes her whack her. Or else she's so crazy that Mio has to take the "straight man" position and drag her into line. While Ritsu is for sure a bit of a leap-before-you-look, both-feet-in-mouth type, you do see in some episodes how she bothers Mio specifically to get her to become more comfortable, distracting her from the scary parts of a new situation. Mio can focus not on what scares her, but instead on the fact that Ritsu is being a total idiot.
And we all know Ritsu isn't all about the craziness. She's not a total derp like Yui. Just look at the "love letter" episode. I think she swallows a lot of her own sensitivity for various reasons... and I think part of that is because she has to be full of confidence to cover for both Mio and herself. If Ritsu was insecure, no way would Mio go along with her. And besides, she's got a reputation to uphold. ^_^
tl;dr, Mio is the anchor for Ritsu's wild side - but Ritsu is the one who drags Mio into the unknown. They balance each other perfectly. And that's what makes their relationship so great.
(/rambling fangirl rant)
Yes yes yes, all my yes.
As for the story, yes yes yes, all my yes.
