[ja] add 〜まい form

[khaitruong922]

Closes #1358

[codspeed-hq]

CodSpeed Performance Report

Merging #1361 will not alter performance

_{Comparing khaitruong922:mai-form (85cd795) with master (601633e)}

Summary

✅ 3 untouched benchmarks

🆕 2 new benchmarks
⁉️ 2 dropped benchmarks

⚠️ Please fix the performance issues or acknowledge them on CodSpeed.

Benchmarks breakdown

	Benchmark	master	khaitruong922:mai-form	Change
⁉️	japanese transformations (n=59)	15.3 ms	N/A	N/A
🆕	japanese transformations (n=61)	N/A	16.1 ms	N/A
⁉️	japanese transformations-full (n=160)	34.4 ms	N/A	N/A
🆕	japanese transformations-full (n=166)	N/A	36.2 ms	N/A

[Casheeew]

lgtm