Oval Butterflyfish (Chaetodon lunulatus) ミスジチョウチョウウオ also Pinstripe Butterflyfish
The Oval Butterflyfish are fairly common and usually travel around in pairs.
If you noticed a little blotch on one of the stripes of the Oval Butterflyfish, it is part to the pattern.
A juvenile Oval Butterflyfish hiding in the coral.