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).
After the Alka-Seltzer tablet was added to the hot water the tablet should have quickly dissolved, taking some 20 to 30 seconds to do so, depending on the exact temperature. After the tablet was added to the ice-cold water it should have taken much longer to dissolve, with most of the tablet disappearing after about two to three minutes, but with some bubbles still apparent after six minutes or longer.