Hindi and Sanskrit are said, by linguists, to belong to the Indo-European languages or Indo-Aryan language and to be closely related to English. On the other hand, people do not really know which group the Japanese language belongs to, although many believe that Japanese is related to the Ural-Altaic language.
According to linguistic theories, then, Indian languages are more closely related to English than to Japanese. However, I personally think that Indian languages share a closer relationship with Japanese than with English, and that it is faster to learn Japanese through the use of Indian languages. The following is a small illustration of this.
The title of this website is: インドで日本語.
Its English transcription is: Indo de Nihon-go
It is written in Devanagari as: इन्दो दे निहोङ्गो
(N.B. Japanese ए and ओ are short consonants and are pronounced like ‘e’ as in ‘pen’ and ‘o’ as in ‘pot’.)
Since Japanese and Devanagari both use syllables as the smallest unit of sound, rather than separate vowels and consonants as in English, the above Devanagari transcription produces a more accurate Japanese pronunciation than does the English phrase.
Its translation in English is: Japanese in India.
The translation in Hindi is: भारत में जापानी.
As you can see here, the similarities between Indian languages and Japanese do not end at their use of syllables as elementary sound units, but they share a relationship even at the grammatical level.
The Japanese language makes extensive use of post-positional particles similar to Hindi, and the placement of each word within a sentence is relatively free as long as a noun and a particle stay together. The sentence structure of Indian and Japanese languages are SOV-style, whereas it is SVO in English.
I hope I have illustrated the benefit of learning Japanese by linking Indian languages and the Japanese language, rather than using English as an intermediate.
Enjoy learning Japanese!