In a Jain context, when eating in Japan you can enjoy many vegetarian options, but you’ll want to choose carefully to follow the Jain rules (especially about non-root foods and avoiding onion/garlic).

Key points for Jain-friendly eating in Japan:

• Favor plain, non-root foods: steamed rice, plain tofu dishes, seaweed (wakame), edamame, cucumber, avocado, mushrooms (some Jains avoid mushrooms; many avoid root vegetables, so check individually).
• Avoid root vegetables: potatoes, onions, garlic, carrots, radishes, beets, ginger (in strict practices), and any other root crops.
• Be mindful of stock and flavorings: many Japanese dishes use dashi (fish stock) or bonito; ask if there’s a vegetarian stock or no stock at all.
• Dairy is allowed in most Jain practices, so you can look for dairy-based dishes like plain tofu with sesame, dairy-free alternatives if you prefer.
• Look for pure vegetarian options or “shojin ryori” style vegetarian meals in some temples or vegetarian-focused restaurants, but always confirm that no onion/garlic and no root vegetables are used.

Practical tips:

• Learn simple phrases in Japanese to convey your needs, e.g., “Watashi wa rēzun no shokuryō, awa arimasen. Niniku to tako no dōru wa irimasen.” (Not exactly precise—have a local help you phrase “I follow Jain dietary rules: no onion, no garlic, no root vegetables.”)
• When in doubt, order plain white rice, tofu dishes without garnishes, and steamed vegetables (if non-root) or simple seaweed salads, and ask the caregiver or chef to confirm ingredients.
• If traveling to a temple or temple-affiliated restaurant, inquire about their kitchen rules and whether they can accommodate Jain restrictions.

If you’d like, I can tailor a short, easy-to-say cheat sheet in Japanese for showing to restaurant staff that covers “no onion/garlic, no root vegetables, dairy allowed.”