Chainer now provides official install script for Google Colaboratory. See chainer/google-colaboratory for details and examples.
Use the following snippet to install Chainer & CuPy (with cuDNN) on Google Colaboratory.
Make sure to enable GPU (
Change runtime type >
Hardware accelerator >
GPU) on your notebook before running the snippet!
!curl https://colab.chainer.org/install | sh -