Who's she heal?
Is this also part of "glimpse from the future" extra? Would like to see full version of her when doing quest... Or maybe war.
A random victim of a monster attack most likely. Sara's a healer on the battlefield and Kamejiro's done a few scenarios in the past of her getting messed up trying to heal casualties, or failing to heal them.
The "glimpse of the future" designation isn't in the raws but something I add for context. You can treat them all as soft-canon after arc 1, when Sara and Natalia get their new outfits, but they aren't specific events to be covered in the main story. This one was just a little less structured so I left it out.
Every x.1 chapter is a paired extra Kamejiro releases the day after each chapter. Kamejiro does them partly to assure it'll get more yuri, but most likely because many of the Japanese audience have read the original twitter version, which ended at the point they got those outfits and the actual adventure began. It's a way of letting that continue while the main story catches up, without spoiling much.