Can I apply for a Japan visa from Thailand with a DTV visa as an Indian national?

I am not sure 100% but when you ask for another visa, you have to ask from your country of residence. And DTV is a tourist visa so you have to apply from India if this was your country of residence before the DTV.

Did you actually look on the Japanese Embassy Website in Thailand? The requirements for a non-thai national are outlined below.

2. Conditions for making your application in Thailand

In principle, you should have a legitimate long term residency in Thailand. You are kindly requested to show us the following documents:

Thai visa (Non-immigrant O, F, ED etc., rather than Tourist Visa) in your passport

Thai re-entry permit

Thai work permit (for business people) or certificate of enrolment from your school in Thailand (for students)

I want to do the same , I’m from India too let us know when you have the information

Email and Check with the Japanese embassy.

You apply where you want but you have to stay if the country yiu apply

You should check the threads, similar question has been asked.