Been wondering that myself. I haven't seen everything Mirei has done but what I have seen was very good. So good in fact she reminded me of a young Miki Sunohara. I know that is saying a lot but if you check out:
You'll definitely see what I mean just in how she works her tongue. I HATE what they have mostly used her for. So many of her flicks is just her getting treated like a whore while getting fucked by multiple guys. I'm sure that makes some guys happy but she is too good of a performer to be doing the same thing over and over again. It's why I haven't watch all that many of her flicks even though she's had well over a 100 appearances. I wish someone like Glory Quest, Aroma, or Oppai would sign her up and make good use of her talent.
I really could not get into her when she was the most active. She seemed very vanilla to me. But I watched video you recommended and I was impressed. She reminds me more of Mao Hamasaki than Miki Sunohara in her build, enthusiasm, and her ability to squirt. They should do a duo flick.