Ria Ross's visible disappointment also affected Kai. They could somehow understand the reason after her explanation. It could be said that the reality was different than their expectation, or at least, it wasn't possible to reach the expectation yet in this era and technology.
"Anyway, you already have an increase in sharpness. I've read the report about you fighting the turtle that led you to change with Michelle. With this Vibration Sword, you should be able to cut its shell… probably." Ria shrugged and rose from her seat, walking toward an alchemy table with many kinds of tubes containing weird-colored fluid.
Kai's eyes followed her, and a weird expression appeared on his face when she walked back and brought one of the tubes.
"And this is my real birthday present for you." Ria shoved a tube containing a blue liquid into Kai's hand.