So Yukikaze here represents a lone ringed secretary ship you see in PvP owned by retired player, basically leaving her to guard the base until the end of time (server closing down).
Edit: apparently this was just epilogue of the manga titled The Girls of the 99 Fleet by this artist.
Updated
When It is UnrequitedHuh?The EndThat's the rumor that's been circling among the expedition regulars. Unidentified fleet girls of various classes, but they always have a wedding ring on. ...they always have a ring on.If I'm not mistaken...But rather than actual wedding rings, I think it might just be a simple accessory. Their appearances are almost identical to the same ships in our fleet.