Sasameki Koto had an April Fools release (31) that was subsequently deleted, but the red "(c31)" still appears next to the name in my reading list.

(And while I'm thinking about it, what's up with that series appearing as "Sasame Kikoto" in my reading list and "Sasameki Koto" in the series page title?)

Fixed

The reason why it appears like that is because you added into your list as "Sasame Kikoto" instead of "Sasameki Koto". To fix it, just delete it from your list, then re-add it under the name you want

A just ruler amongst tyrants