Feature Request: use japanize-matplotlib instead of direct setting

[tsuyoshicho]

see

• uehara1414/japanize-matplotlib: pip install して import するだけで matplotlib を日本語表示対応させる

problem

When system do not installed IPAGothic, then fall back DejaVu font and japanese render fail(tofu).

resolve

Use japanize-matplotlib package, this package contains font file(IPAexGothic). Therefore, Any system(Win/Mac/Linux) render success.