Since I recently introduced RubyMine, I would like to list what I have set. We plan to update it from time to time.
Open Preferences → Plugins on the menu bar and install a plugin called "Japanese Language Pack EAP".
(Since it is still in Early Access, there are some English words, but it can be used without problems for normal use.)
Open the project tab on the left, open a menu like the three-point reader at the top, and check the following
Introduce a theme that suits you. Of course, you can set the color schema from 1 by yourself, but since various themes are open to the public, you should first check if there is a theme you like. The following are recommended themes and icon setting plugins.
If you set it yourself The color of the file name can be changed in Preferences-> Version Control-> File Status Colors. https://intellij-support.jetbrains.com/hc/en-us/community/posts/206694189-Where-can-you-change-the-color-of-the-filename-text-on-a-tab-that-is-opened-
Refer to the link below to set the interpreter that suits your environment. Otherwise, it will not find the gem method etc., so it is essential.