[ja] Apply bc3f922f2549e44524dc11301d1e53c984b14a1b

The number of hunks is different from the original commit since some changes were already applied to ja translation and, as a result, hunk 20 of original commit became unnecessary.
[ja] Apply 4 commits to ja tree

Hunk 1: e1d6628e2f355577a2d38a9fd93db741631a4a40
Hunk 2: 0c34253095f327209aceab8b3170f93b0c0c4ed9
Hunk 3: 66d1feb527eeb302060e7a67db48816f86ce85e7
Hunk 4: ef5f3e63371b6172c13bb1d51f7f010bca423fa6
Merge pull request #409 from harupong/ja-chapter5

[ja] Update chapter5