Soma says, "Not understand why you worry." Never let it be said that Soma is not straightforward / at least, they haven't yet learned that there may be a benefit to being anything else. Thin brows arch and there's no judgement, just honest confusion, because Sakura knows what Soma is — at least as much as anyone else does. Sakura knows Soma will come back when she dies, missing some small remembrance and perhaps with a new scar, but back nonetheless. Sakura knows Soma is a weapon and not a person, that 'Soma' is a fiction dreamt in lieu of history. But still, Sakura worries, tries to protect her, tries to keep her / this body from death. Soma isn't sure whether the grief / gratefulness she feels is hers or the other one's. Soma says, "strange to worry for this body."