Ogata's anger is a little understandable, considering the clothes fiasco. But I think a lot of her anger is towards herself, and stems from her own realisation that she had a rival this whole time that she never knew about. She tried to take things slowly, not push too far, because she didn't think she had to. And now all her several-year-long effort has been wasted, cause Mashuu was never looking at her in the first place. I feel for her. But it's also a little rude to tell your crushes crush that he likes her. She didn't know for sure that Satoko knew.
I like Ogata. She, like all the other characters, is just a person with emotions who doesn't know how to deal with them. And I think despite an outburst of anger, she's truly a kind person. I hope she gets herself a good dude.