Little detail I noticed just re-refinalizing a few episodes’ subs (per my post last night):
Judai loses to Ryou in episode 8 after challenging him knowing he was #1 at the Academia, and part of the Kaiser’s strategy was using De-Fusion/Fusion Undone to split his Cyber Twin to go into Cyber End.
A few episodes later, Judai seems to have made it a learning experience as he debuts his first use of De-Fusion on poor Ayanokouji (Harrington).
Did he pick it up as a sign of his respect for Ryou after their duel? Possibly? 🤔