"I guess it's time to ramp things up a little bit." Kazuichi let out, showing off his newfound powers for the first time.
Unbeknownst to everyone, Kazuichi had been hoarding meteorite ores in his free time, absorbing as much as he could within the day to maximize his growth as a Hybrid.
With the new information about the Hybrid levels and Blood Arts, he knew that there might come a time when he'd face someone potentially stronger than him. As far as he knows, they may be someone who'd already reached Hybrid level IV or V.
Japan is a huge place, after all, and he couldn't lie on his laurels the entire time. He may be a shut-in, but he values practicality over laziness.
It was only recently that Kazuichi broke through stage III of his hybrid level. His control over his Blood Arts had also increased in proficiency thanks to Arisu's spartan training. Those factors helped him reach a higher level— a level that Arisu never knew he had attained.