Like January, February is a good time for visiting Japan as the weather is usually sunny and dry and sightseeing spots are not crowded. The downside of a visit in winter are the relatively short days (sunset is around 5:30pm in Tokyo) and the vegetation's barren state.
1 A healthy person drinking approximately 2 liters of water per day makes 800 to 2000 ml of urine per 24 hours (4).  If the urinary system is healthy, the bladder can hold up to 16 ounces (2 cups) of urine comfortably for 2 to 5 hours (5).
There is no exact science to find out how long it will take for your body to digest food. Hydration and digestive health affect how long it takes your body to digest food. Food moves faster through the digestive track when the body is hydrated. You can estimate how long it will take based on the makeup of the food you eat. For most healthy adults, digestion takes between 24 and 72 hours. Carbohydrates digest faster than proteins, and proteins faster than fats.