add Japan-target age buckets

[takahashimonotas]

Issue Type: Improvement

Relates To: #266

Changes Included:

• Add some values to agebuckets enum. Japan-target only age buckets

Check List: No changes to tests or examples.

• [ ] Includes adequate test coverage for changes made.
• [ ] Includes new or updated documentation.
• [ ] Includes new or updated usage examples.

[CLAassistant]

All committers have signed the CLA.