Well, it can`t be called subtext anymore since one of the lady is confirmed into woman
Possibly yuri crush
would be a slightly better tag for this story but even that doesn't seem quite accurate. If it wasn't for the chapters about the guy on the train I would say this was an example of Ace and Lesbian life partners.
I really have zero investment in tags per se, but on an abstract definitional level, I don't think the mere presence of a woman who is into women makes a story "yuri"--I feel like some sort of relationship element (although not necessarily between MCs) is a required active ingredient. Otherwise, it might be Incidental Lesbian
, maybe?
In fact, re-reading the first few chapters makes it a bit hard for me to believe that Shima's out sexuality was intended from the very start--we get a lot of "mutual uselessness" cues, like each of them thinking how cute the other is, "what am I, your girlfriend?" jokes, the het guy arc, etc.
In terms of "yuri crush," Ise-san and Shima-san clearly love each other as friends and running buddies, but have we actually had any "wish for more" cues from either side of the equation? (We might have, but I'm not remembering any right now.)
Sure, both of them are adorable, and I'm into yuri, so I'd love to see them get together in some plausible way. But mainly they're incredibly fun to read about just as they are, so I'm also fine with "steady as she goes."