Longfin Bannerfish (Heniochus acuminatus) ハタタテダイ (size 25cm maybe with the longfin)
The Longfin Bannerfish looks nearly identical to the Schooling Bannerfish. The Longfin Bannerfish is usually seen singly or in pairs. It also has a slightly longer snout. Amami 2024
The Longfin Bannerfish has more room on the snout for a larger black patch. Amami 2024