[ja] Apply ccffb46d687bfb1c005965e0b49e27d05e816673
[ja] Apply bc3f922f2549e44524dc11301d1e53c984b14a1b
[ja] Apply b294744d98a6f6cdbc3508b0058f8616147c1596 and fix typo
Merge pull request #407 from harupong/ja-chapter1

[ja] Apply rest of the unapplied commits to ja chapter 1
[ja] fix bug introduced by #407
Merge branch 'master' into fix-chapter1