When I lived in Japan one of my friends was celiac and would constantly be like "can't, it has gluten" at things I never would have even thought of 😭 sending good vibes to the gluten warriors out there
Buckwheat is naturally gluten-free, so soba seems like a safe choice. But most soba in Japan is a blend of buckwheat and wheat flour. Unless it's labeled 100% buckwheat (十割そば, juwari soba), it likely contains gluten.