A few years ago, I decided to start collecting kaiju LaserDiscs. Its a niche thing to collect, and they're generally pretty cheap if you know where to look. Ebay is a terrible place to shop for these, because sellers are trying to gouge prices, the sleeves are usually way more worn, you have no idea if the discs have been tested or if they're rotted, and the sellers have no idea how to pack and ship a LaserDisc.
Since 2016, I have pretty much managed to get a complete collection of Toho-produced Godzilla LaserDiscs. That includes all analog audio releases, digital releases, box sets, etc. I have the Toho SF Encyclopedia, which to my knowledge contains the only official home release of any footage from Half Human. I still need the standard Japanese release of GINO, but I'm not rushing for it. I've gathered other Tokusatsu releases from Toho, Daiei, and other studios. So far, I've strayed away from things like Ultraman and sentai, because they are their own rabbit holes, and I only have so much space to store these for now. I have a few spots missing in my American-produced collection and/or I need a replacement because some of my American discs are rotted.
I've also invested in some nice players, and I'm trying to look into solutions to digitize these, since some discs have versions of these movies that never made it to DVD or Blu-ray (such as the AIP Smog Monster). I have a Runco LJR I, which is nice because it doesn't suffer from the "CLV Smear" that causes a player to add a horizontal smearing effect to the picture. I have another player on the way that is very similar to the LJR I, but adds support for AC3 surround sound. I've also kept a Pioneer CLD-D704 as a backup, but I think I'll sell it when my new player gets here.
And somewhat related, but I think I might have a complete VHD collection of Toho's Tokusatsu & Kaiju releases. VHD was a failed competitor to LaserDisc, and the format never left Japan. The discs are 9-inch vinyls that are housed inside of a caddy. If you happen to remember CED, then VHDs are very similar to that. I just recently got a VHD player in the mail, and the playback quality is very similar to VHS.
I need to take updated photos of my collection, but here's a few that are a bit outdated: