For safety reasons — yours, others, and the entire network’s — please do not use umbrellas or kites in stations, or in particular on the platforms.
Power lines at stations with electric lines carry very high and powerful voltage (25,000 volts!). Anything touching these live wires is almost certainly going to be hit by one very powerful shock. If this hits a live human, the result would almost certainly be instant electrocution and death.
Umbrellas and kites are “tall items” as they can reach, or can indirectly reach, power lines. If your umbrella or kite happens to touch these live wires whilst you are holding them, the result would very likely be instant death.
This is why, as a safety precaution, it is prohibited to use umbrellas or fly kites, especially on platforms with overhead power lines — which includes all HSR stations. If you have an umbrella or kite with you, please pack it away in your bag, suitcase, or other item of luggage.
If it is raining or snowing, please mind your step, walk carefully, and, where available, proceed to a part of the platform with overhead cover. At the same time, due to safety concerns, you may not use or raise sticks or portable tripods, or photograph using these on the platform. This means you must also not use selfie sticks of any kind. If they happen to touch the overhead power wires, the result would almost certainly be fatal.