Where have you seen it other than here? That would be helpful for both yourself and us to search further.

The usual search engines are returning nothing, and the resolution suggests it's probably turn-of-the-millennium in terms of age, and might originally have been slightly wider...

So possibly was on some classic manga artist site, maybe on one of the old shared hosting sites with user names starting with ~tildes, which fell off the net long before there was any chance for it to be properly archived. Maybe the artist died, wasn't able to renew their hosting or at least to respond to emails asking them to log back in to keep the account active, etc...