I opened the package, and it was firm! I expected that, but it completely flattens the meluna soft in a squish test without bending at all... haha. My infuser box was broken, but I received a replacement today, which I haven't tried yet.
On the first day of my cycle (pretty light) I inserted it with a punch-down fold, which is the fold I'd always used with the Meluna Small Soft. I actually felt it spring open! It didn't hurt, though. I went to sit down, and I felt the stem poking at me. After adjusting it, I didn't feel it anymore and never had the problem again, as I now knew how high up it had to sit. I thought I might feel the rim or something since it's such a firm cup, but nope. I had very little leaking, much like with the Meluna Soft.
Removal was another story. I reached up to grab the stem and my fingers kept slipping. The grip rings on the Yuuki are so flat, they might as well not be there. The stem is also extremely stretchy. Eventually, I did manage to get a grip on it and broke the suction. Then I pulled it down a little, and I could tell it was going to be hard to get out because the rim was not flexible at all.
With the Meluna Soft, I didn't ever need to break suction or fold the cup, just get a good grip and pull it all the way out. With the Yuuki, it had to be completely flattened into a C. Still, I emptied the cup, reinserted it, and went to bed. I woke up the next morning, and lo and behold, no leaking at all! Amazing.
I emptied it about two more times that day. One of those times, I got so angry with the stem that when I finally grabbed it, I went too fast and pulled it out without folding it enough... Ouch. I think it might have torn my hymen a little as it hurt for the rest of the day. Eventually, removal was such a pain that I switched back to my MeLuna for the day part of the rest of my cycle. The Yuuki did leak the second night.
All in all, my first run was a mixed bag. I love that I might be able to sleep without leaking, but I hate the stem (imo, a giant design flaw on Yuuki's part) and how I have to fold it into a C to remove it lest I experience horrible pain and hymen tearing. If anyone has suggestions on how to make the rings more grippable, I'd appreciate it.
I will definitely keep practicing and it's not a terrible cup (I don't regret buying it), but I don't think it's my perfect match.