Mitsuki competed in the Inter High School Championships at the end of January, where he placed 3rd with a total of 207.31. So he should be healthy by now. I think I read a while ago that he was planning to stay in juniors. I am guessing Sena will want to turn senior though, especially if Coupe du Printemps goes well for him (which is likely, barring meltdown).
Sena won Coupe du Printemps! His total was 183.62.
Thanks for the Mitsuki info too!