Shachihoko.

Shachihoko (鯱鉾, しゃちほこ) is a sea monster with the body of a carp-like fish and the head of a tiger or dragon-like beast. Its dorsal fins are sharp, its tail curves dramatically upward, and in architectural form it stands with its head lowered and tail thrust toward the sky. The image is both aquatic and martial, a creature of the sea repurposed for the roofline.

That stylized posture became so famous that shachihoko-baru came to describe stiff or over-formal bearing. The beast is therefore not only a guardian but a pose of power, a silhouette of vigilance made permanent in ornament.

In folklore and architectural belief, shachihoko stores vast amounts of water and can call rain or spit out what it has swallowed to extinguish flames. This makes it a natural protector for wooden castles, temples, and mansions constantly threatened by fire. Placed in male-female pairs at the ends of roof ridges, shachihoko guard by watching, balancing, and promising water against disaster.

Their meaning also became political. Large and richly decorated shachihoko signaled wealth and rank, so the creature moved easily from practical fire-warding belief into feudal display. The roof guardian became an announcement of status as much as a supernatural safeguard.