User blog comment:Crimson and Darkness/Volume 24 discussion blog/@comment-73.57.25.92-20180113184952/@comment-2601:8C:601:5692:70F4:6327:4182:E9AD-20180117025834

@Bennia, while you're right that the name change is symbolic of their full reconcile, unless you've read that in the raws, I think you might be a little off their. I'm pretty sure that Jap wiki indicates that it was Koneko herself who chooses to embrace her original name and go officially by "Toujou Shirone", while in Kuroka's case she chooses to adopt the surname "Toujou" that was given to her sister by Rias. IN MY OPINION For Koneko, this represents her fully accepting the part of herself she'd been rejecting until now. For Kuroka, who'd always insisted on using her sister's original name instead of the name given to her by Rias, this represents her accepting the part of her sister that had up until then rejected her (as well as the part/time of her sister growing up that she hadn't been a part of).

If I made a mistake somewhere, my apologies.