What Is Hatsu Sekku? To start, we need to look at the Japanese language and brush up on some history. Hatsu (初) means first while sekku (節句) are one of five annual ceremonies that were traditionally held at the Japanese imperial court. Most of these celebrations have the roots in China and came to Japan during the Nara Period. In the Heian period (8th-12th century) sekku caught on — probably because they were an excuse to show off one’s fabulous wardrobe and upstage others in the imperial court.