Actually, Sada's lyrics includes 'Shoronagashi ga hanayakani' (spectacular Shoronagashi), and also his group's first album "Wasuremono" contains "Shoronagashi" which includes the sounds of firecrackers during its lead-in.
実は、さだも歌詞の中で「精霊流しが華やかに」と書いており、グレープのデビューアルバム『わすれもの』では『精霊流し』の導入部に爆竹の音が入っている。