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
An occasional guest bed in the living room
If your Latvian home uses the living room for overnight guests, plan the morning changeover before choosing the bedding. Folding can restore the sitting area, but the futon first needs a place to air and dry. Check whether that position can remain available while the room returns to everyday use. Putting bedding straight into a cupboard after a guest leaves may be convenient, but only if it is already dry.
HIMARI is 210 cm long; SORA is 200 cm. Measure the open footprint around furniture and doorways, then check the selected width and full supporting surface. A firmer preference may lead you towards HIMARI, while SORA's fuller cushioning may appeal differently. Guest preferences will vary. Both fold into thirds, but their folded width and handling effort still need room in your plan. Choose for the routine you can sustain, including underside checks before the bed goes back into storage.
How do I choose between HIMARI 日葵 and SORA 宙? · How do Japanese shikibuton sizes compare with local bed sizes?