S P O T ／ SPOT-332

Tsuzumi-iwa (Ponpon Rock)

鼓岩（ポンポン岩）つづみいわ（ぽんぽんいわ）

On the summit slope of Mt. Senkoji in Onomichi, overlooking the maze of channels and islands that make this hillside town famous, sits an unassuming boulder that does something no boulder should: it sounds. Tap its surface with a pebble and a hollow inside answers back with a dry, drum-like "pon-pon" — hence its nickname, Ponpon-iwa, the Drum Rock. The acoustics are only half the story. A deep gash scars its right flank, the mark of chisels left when 16th-century stonemasons began splitting the rock to haul away as wall material for Osaka Castle, then abandoned the job; identical wedge scars dot other boulders across these hills, relics of a quarrying campaign ordered by Toyotomi Hideyoshi around 1583. Some scholars read the summit's scattered megaliths as ancient iwakura — sacred rocks once worshipped as vessels of the gods — which would make this drumming stone a single object layered with natural oddity, prehistoric faith, and feudal labor history all at once. A poetry monument to the scholar Rai San'yo stands close by, and from here the whole Onomichi channel opens out below.