Right after fninishing Pain Hard (35.2k) TI, but before I came to the rewad screen, i was attacked by a single challenge: Ginkaku.

After defeating him, I returned to the flip-card screen for my TI rewards.

It his some kind of gimmick?

The screenshot is kinda bad, but before Shisui put up his barriere, I was in a battlefield which looked like a scroll (?). It seemed wired, since he was extremly week anyways.