There would seem to be quite a number of possibilities, including:
Japanese business interests in India were extensive between the two world wars. Putting this together with "In the 1880s, 23 percent of prominent Japanese businessmen were from the samurai class; by the 1920s 35% were." (as cited by ed.hank from Wikipedia Samurai in his comment), it is probable that there would be "a young man from a wealthy, samurai family" in northern India. By the 1920s, India was the 5th largest export market for Japan. On Japanese economic interests in India (referring to Japanese merchants in the period 1914 to 1937):
...these businesses prospered and were supported by Japanese banking
and commercial houses in the subcontinent....Japanese companies
explored every aspect of India and its economy, and although major
activity in cotton, banking, shipping and related activities was
concentrated in Bombay and Calcutta, Japanese businessmen were also to
be found in remote up-country corners of the subcontinent....Thus by
the 1930s India had become a larger export market for Japan than
Source: Christopher Howe, 'The Origins of Japanese Trade Supremacy: Development and Technology in Asia from 1540 to the Pacific War' (1999)
Dentists (aka Spies)
Japanese espionage was highly active throughout Asia from before World War I and throughout the 1920s and 1930s across the Indian subcontinent and in South East Asia. Dentists, barbers and businessmen were among the suspects. For example, in India,
One British Indian Army officer noted: ‘There was a Japanese dentist
in every garrison town in India looking after the teeth of the British
Other Ranks and their families . . . They provided cheap and excellent
treatment and no doubt learned much military information.
Buddhists and Political Activists
With specific reference to the 1930s and including Northern India (Rajasthan),
...a number of Japanese Pan-Asianist and Buddhist activists traveled
to India to establish links with the Indian nationalist movement....
In 1933, Fujii Gyōshō (also known as Fujii Nichidatsu) and Ohkitsu
Tadao, two Buddhist monks of the Nichiren sect, traveled to India to
establish links with Indian nationalists. While Fujii was staying at
Gandhi’s ashram in Wardha, Maharashtra, he sent Ohkitsu to attend the
annual meeting of the Hindu Mahasabha in Ajmer, Rajasthan.
For background, Ekai Kawaguchi, a Japanese Buddhist monk, visited Nepal and Tibet several times between 1899 and 1915 and was "the first recorded Japanese citizen to travel in either country". In 1909, he wrote about some of his experiences in Three Years in Tibet (click the ink for the full text). Many others followed and, as three of the four "main pilgrimage sites listed by Buddha himself" are in India, it is highly likely that most of these pilgrims visited them.
There were also many Japanese artists who visited India from the late 19th century onwards (though whether any were from wealthy, samurai families is hard to tell):
Since the late 19th century, India and Japan have shown interests in
each other, beginning with Swami Vivekananda’s visit in 1893.
Continuing well into the 20th and 21st century, further visits by
Japanese artists in particular, have ensued.
Among these visitors was Yoshida Hiroshi (1876–1950), "the most successful Japanese woodblock printer of the early twentieth century"
From November 1930, Yoshida spent over four months travelling in India
and Southeast Asia, sketching and painting the sights.