The official languages of India are Hindi and English.
Despite saying that, Hindi is fine in North India, but in fact it is not so well understood in South India.When it comes to that, I rely on English.
But again, Indian English has a pretty terrible accent, and even British people often get angry. So we will compete in Jinglish (Japanese English)! Let's go with a feeling like that. If you can say a single greeting in Hindi, your trip may change in a fun way.
If you are not confident in your language, it is safer to ask for a Japanese guide in advance. As a traveler who has come to an environment far from Japan, he tends to become anxious and bearish if he does not understand the language. After arriving at the site, there may be people who come to me like "Japanese Dekimasu, Guide Shimmers", but it is a good idea to be taken to a suspicious office and be crushed in a situation where you can not escape. So be careful.
In that case, it is easier to travel if you make a reservation for a guide from Japan in advance.The trip is basically for fun. If you make a reservation with a travel agency, you will be picked up at the airport, check-in at the hotel, and the information and explanations of the sights will be in Japanese. You can feel free to ask.
Cultural customs cannot be understood just by looking at the guidebook!