There is an unofficial Japanese Nix Community on Discord:
The Japanese title is: Nix日本語コミュニティ
Communication mainly happens in Japanese.
- The server currently has about 100 users, and there is a spurt of activity once every few days.
- There are quite a few people who are very knowledgeable about Nix/Nixpkgs/NixOS, and will answer questions in Japanese about any of these.
- There are a handful of people using Nix professionally at companies in Japan.
- There are a few Nixpkgs committers active on here and will answer questions in Japanese about PRs to Nixpkgs.
(Oh, and for people that aren’t aware, there is also an unofficial NixOS Discord for English-speaking users: Nix/NixOS (unofficial))