Here’s what Nelson has to say:
Now known as “Children’s Day” in Japan (a National holiday), this is the day when sons are traditionally honored. Most notable are the large koinobori (carp) banners that are flown – one for each male son. The carp is considered as the most spirited of all fish, able to overcome obstacles such as strong currents – hence, it serves as a symbol of the desired strength and success of the family’s male childen.
I have incorporated other aspects of the Japanese culture – Father enjoying sake; a katanakake (sword stand); a small Zen garden, etc.