Mizuki would be surprised, or even incredulous, but the latter has shocked her enough to warrant any more of a reaction. She stands up slowly, and her knees already feel as though they might start creaking under the weight of her body.
"I didn't know you were strong enough to carry a whole twenty-year-old," she says when she meets Shoma halfway, offering to take the lanterns out of her hands before she accidentally spills the fire onto the ground.
"We live and we learn," Shoma explains, continuing to trudge towards the bark of the tree, this time with more ease, partly since she doesn't have the lamps to worry about.
Otherwise, it's because she doesn't want to slow down and ditch him halfway on the ground because of her exhaustion.