Japan is exceptional at assimilating foreign influences and making them uniquely their own. Buddhism is one example and its origin in India cannot be denied.
After some resistance to the threat of Buddhism supplanting native Shinto deities, the Japanese embraced this imported philosophy. Now many temples are co-located with shrines and some holy sites incorporate a fusion of Shinto and Buddhism known as Shinbutsu-shūgō.
In many ways, Japan has preserved much of what has been lost since Buddhism fizzled out in much of India or was syncretized with Tibetan traditions.
To illustrate, Shingon Esoteric “Vajrayana” Buddhism insists on the study and use of the largely extinct Siddham Sanskrit characters as the baseline language for its mantras, dharanis, and invocations.
The documentary, produced by the Indian government as part of a diplomatic initiative, highlights the history as well as some key locations within Japan where such deities are prominent.
A shorter version is also available:
Having visited several of these locations, including Tokyo's Takahata Fudo and Kyoto's Toji during my studies of Shingon Mikkyo, seeing the Indian origins and influences is, well, enlightening.