Without re-reading the manga just to find it, I’m genuinely curious at what point he started doing the double spike in his hair instead of the one.
Obviously it isn’t unlike the characters to have a different hair style here and there, but this one completely flew under the radar for me for quite a while.
Since Okarun and her conflicting feelings about him seem to be the only part of Momo’s old self that seeps through, I’m certain that there is no “cure” to her amnesia other than her love for Okarun triggering her memories. I don’t know how it will happen, but I don’t think there will be some external event that gives her memories back, but rather something internal surrounding her relationship with Okarun. As that is the only thread tying pre and post amnesia Momo together.
I’m still going the route that she will somehow see into Okarun’s memories as the trigger.
That being said though for those who are getting patient, if we break down the manga by seasons of the anime, it looks like we could be in the middle of the 6th season. So assuming that the amnesia will be resolved by the end of that season, in theory we should only have 10-20 more chapters left of it.