From animetosho owner:

After managing this project for roughly 15 years, I've decided that I want to move on to other things. This was not an easy decision to make and is something I've been considering over the past few years yet reluctant to do. The amount of time and effort I have poured into AT is basically a significant portion of my life now, so throwing it away is still an uncomfortable thought (especially considering the contributions others have made here). Nevertheless, it's something I always knew I had to do at some point.

Anime Tosho has been a lot more successful than I had originally imagined, and I'm proud of what it has achieved. I see that it delivers value to a sizable audience (myself included) and some downstream projects rely on it. Unfortunately I can't shut down this website without it affecting anyone else, so my apologies for disruptions my selfish decision will cause.

I don't intend to leave AT in a semi-unmaintained state (unlike cough Nyaa.si), despite the upkeep being relatively low. I also don't intend to hand over control of AT to someone else - I encourage anyone who wishes to manage a service like this to do so under their own name and terms. Thus I believe a shutdown to be the best course of action.