The No. 18204 is the carpenter replacement blade for the Z-Saw Tuck-In 240 Carpenter (No. 18004), the folding saw for precise work in lumber, plywood and laminated board.
It's the same 240 mm (9.4 in) blade the Carpenter saw comes with: 0.70 mm thick and nickel phosphorous plated, with impulse-hardened universal teeth at a 1.75 mm pitch (15 TPI) for rip, crosscut and angled cuts, and a 0.95 mm kerf. It's a pin-fit blade, so when the teeth dull you swap the blade and keep the handle.
Z-Saw's maker, Okada Hardware, has made saws in Miki, Japan since 1943 and was the first company in Japan to impulse-harden saw teeth.