You can create a second Apple ID set to "Japan" to download these apps without losing access to your primary home country account.
Typing in Japanese on an iPhone is primarily done through two different keyboard layouts. jp.iphone.
Some critical local apps (like specific convenience store printing tools) are only available in the Japanese region. You can create a second Apple ID set
Features bite-sized lessons and timed tests to help with memorization. jp.iphone.
If you are using your phone to study the language, several high-rated apps focus specifically on the tactile nature of writing.