Choose HIMARI or SORA when the published dimensions fit your room and you can regularly lift, air and keep the bedding dry. Compare the firmer HIMARI with the fuller SORA by personal preference, storage space and the actual local offering. Thickness alone does not determine comfort.
Details to check before choosing
Measure the usable length and width of the floor, platform or bed base, including any raised edges. Compare those measurements with the exact model and size offered for your country. Then check the folded size and weight, and choose a sheet or cover that fits the same dimensions.
After sleep, lift or stand the shikibuton so you can inspect its underside and the supporting surface. Let both release moisture. Air both faces in a ventilated place, turn the bedding over and rotate it head to foot regularly. Fold and store it only when it is dry.
Sources for this answer
A shikibuton that usually stays on its base
A Hungarian buyer may want the feel of Japanese bedding without folding the bed away every morning. That can still make the supporting surface and access for care the deciding factors. Measure inside your existing base: HIMARI is 210 cm long and SORA 200 cm. Check raised edges, the chosen width and full support, then consider how you would lift the bedding to inspect the lower face.
HIMARI's steadier medium-firm response and SORA's fuller cushioning offer a choice of feel, not a universal improvement over your current mattress. Both fold into thirds when you need to air or store them. Check the folded dimensions and weight if you expect to move the bed for cleaning or guests. Leaving it laid out does not remove the need for regular underside checks. Choose a model alongside a practical airing position, especially when nearby furniture limits access.
How do I choose between HIMARI 日葵 and SORA 宙? · How do Japanese shikibuton sizes compare with local bed sizes?