May 5 is Boys' Festival.
There is a custom which hoists the flag which carried out the form of the carp in
Boys' Festival.
You can also see this flag on a Asagiri plateau.
It is a flag of the carp which sails in the sky.
And Mt. Fuji can be seen behind that.
The flag of this carp can be seen from the end of April.
The flag which carried out the form of the carp is called "Koinobori".