[ja] Apply 6f68925573e02c9e7398300f08272a4482851d52
[ja] Apply 483a4e4fc219c058fad7275f3b31db86f71e9283
[ja] Apply d3673c08144c67ef818e785214f90ed1832c6b24
[ja] Apply 0c34253095f327209aceab8b3170f93b0c0c4ed9
Merge pull request #414 from harupong/ja-chapter9

[ja] Update chapter9