>>2809996
The number of Indian residents in Japan is approximately 50,000, of which 11,000 are technicians (IT, etc.), 7,000 are skilled workers (cooks, stable hands, etc.), more than 11,000 are their families, 2,000 are foreign students, 9,000 are long-time residents (traders, etc.), 1,000 are highly specialized workers, and 1,000 are low-wage workers (technical interns).
Convenience store clerks are required to have high Japanese language skills, and technical intern trainees are not allowed to work in positions other than those they are contracted for.
What you saw is probably a foreign student or otherwise a part-time job for a family member of an engineer, technician, permanent resident, etc.