Cost of living in Tokyo is the highest in Japan, a country already known for its high cost of living. The average monthly expense (tuition fees not included) for UTokyo Graduate Students is JPY 137,061 for a single student and JPY 190,457 for students living with their family members. This will include an average rent of JPY 58,227 (for a single student)・JPY 69,179 (for family) and an average cost of food JPY 38,893 (for a single student)・JPY 53,361 (for family).
Reference: "Survey on Student Life Conditions (International Students)" (2018-2020)
However, international students usually spend more on food (around JPY 40,000 or more) due to the difference in the food availablity in Japan. International students living with their families spend 1.5 times more on living expenses than single international students.
Please be prepared for living expenses by collecting sufficient information in advance to ensure that financial concerns do not cause problems in your study/research.