Japanese Language School

No, you can't get direct admission for Japanese hons in JNU because admission process is by entrance test mode then there will be merit screening.
You can get the further info from below given link:
https://www.shiksha.com/humanities-social-sciences/languages/course/b-a-hons-in-japanese-jawaharlal-nehru-university-mehrauli-delhi-268867
The Entrance Test Online Application Available on the Official Website of Jawaharlal Nehru University. Application form for all courses is issued from 15th September 2017.
Hope this helps.

Foreign language knowledge is a value addition. Most of the organisations in India dealing with mechanics and automobiles are Japanese companies and from personal experience, they prefer candidates with knowledge of the Japanese language so that they can send them for off-shore projects, etc. Overall, the scope is good.