A tsunami at the gate of the king makes sure all of his plants get watered. The gate prevents the tsunami from damaging anything inside the king’s home, and the plants around the gate get watered by the water of the tsunami.
These plants are getting watered in June (じゅん), the month they need watering the most. June is a hot month, so it’s good that this tsunami came and got the king’s plants watered when it did.
Currently there are no similar looking kanji which exist in the WaniKani learning system