Japanese has slightly different punctuation; those are simply Japanese brackets, which can be written as【】or 「」 as opposed to the western []. Other Latin punctuation is also different, like ! = !? = ? . = 。etc. Personally I just use Latin punctuation because it looks more crisp to me, but that's a matter of opinion. If I were to be writing an actual sentence in Japanese, not just formatting the title of my UTAU covers, I'd use the Japanese punctuation.