I found some link of the Chainer tutorial page is wrong.
On this page, there are two links "チュートリアルを始める" to tutorial.html.
The first one links to https://tutorials.chainer.org/ja/tutorial.html,
the second one links to https://tutorials.chainer.org/tutorial.html, which is 404 Not Found.
I think the second one should link to https://tutorials.chainer.org/ja/tutorial.html.
I found some link of the Chainer tutorial page is wrong.
On this page, there are two links "チュートリアルを始める" to tutorial.html.
The first one links to https://tutorials.chainer.org/ja/tutorial.html,
the second one links to https://tutorials.chainer.org/tutorial.html, which is 404 Not Found.
I think the second one should link to https://tutorials.chainer.org/ja/tutorial.html.