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).
It is clear that drinking water before and after you eat aids the digestive process. The general consensus on this is that drinking water about 30 minutes before you eat will help keep the body hydrated which results in optimal digestion. For the liver, this is also important as overall body hydration aids in optimal liver performance.