Greetings Riddhi!

Hope you're doing great.

Jawaharlal Nehru University(JNU) is the most reputed university of India. It won't be wrong to say that it's the most promising and premium university that exists today in our country. Now coming back to your question, I'm sure you're talking about learning or taking Japanese course from JNU. Let me enlighten you with the facts, JNU offers 3-year Undergraduate course in Japanese learning. Once you'll finish the course you'll be granted a BA degree in Japanese. 

There are other university and distance learning programs(IGNOU) which offer Japanese learning. Although, most of the distance learning offers the certificate of diploma degree and rest are just as good as a piece of paper. I guess you're looking forward to CSE examination and must be aiming for Foreign Service or to pursue a career as a language translator. I won't suggest or emphasize any institute I'll leave that to your conscience to decide however if you're looking forward to getting a prestigious alumni status then I'd definitely recommend JNU as a right option. 

Hope, this will help. Cheers!