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
Choosing an occasional bed for a room you close between guests
If a room in your Cyprus home is used for guests and then closed again, choose bedding with the changeover in mind. A foldaway futon can return the room to everyday use, but you need a place to air it after the guest leaves. Air-conditioning may make the room comfortable without ensuring airflow beneath bedding pressed against a floor. Check that someone can lift and inspect it before storage.
HIMARI is 210 cm long and SORA 200 cm, so compare each with the usable floor or platform and the space needed to open doors. HIMARI has a steadier medium-firm character; SORA offers a fuller surface. Treat those as preferences rather than a universal guest recommendation. Both fold into thirds, but confirm the folded volume and handling effort against your storage. Keeping floor space flexible works best when care has an equally practical place in the room.
How do I choose between HIMARI 日葵 and SORA 宙? · How do Japanese shikibuton sizes compare with local bed sizes?