In the Language Select screen there are two weird options for Japanese one of them being: "にほんご" and "日本語". I believe "日本語" is the original Japanese, maybe that one version is a simplified one?
This might not be Pokemon-related but I'll post.
One is in Kanji, one is in Kana.
Kids can't read a lot of Kanji (proper Japanese), so Kana is an option.
They both read as Nihongo, which means Japanese. Just different styles.
Source: I speak Japanese