5th May is the Boys' Festival (Tango no Sekku/Kodomo no hi) in Japan. In the Yagishita House in Negishi Natsukasi Koen Park, you can see traditional decorations and experience origami helmet folding.
Duration: Sunday, 21st April to Saturday, 11th May
*Closed on 23rd April.
Address:10 Shimocho, Isogo-ku, Yokohama (8 min on foot from JR Negishi station)
Official Website (in Japanese)