Yamada's First Time. lol I don't like ecchi, but I got into romance anime last summer and this one was just so funny, sex positive, and oddly sweet at times. It's def kinda ecchi though.
You can just search terms right within Element to find public "rooms" (like a Discord Server). There's rooms for all kinds of things. There are private rooms, too, but someone in the room would have to send you a link to it.
I love the Element client for Matrix. I use it with my friends and I have joined a lot of communities on there. It's Discord-like, but I personally find it much easier to navigate than Discord. It's free, open source, decentralized, you can self-host if that's your jam, it's got some solid security and usability features, call quality is great, and I've found it to be very stable and reliable. I'm a little biased because I personally don't like Discord, I find the UI clunky and unpleasant to use, but I love using Element. If you love Discord, you will find Element familiar, but you may or may not appreciate the differences.