Utopia Shiratama is a straightforward day-use onsen complex, so expect gender-separated indoor and outdoor baths and the usual Japanese bathing rules: wash thoroughly before entering and keep noise low. If you have tattoos, plan to cover them or ask staff ahead, since many onsen restrict visible ink; private family baths are often rentable if you need privacy. Bring cash and a towel or be prepared to rent one on site; prices are typically in the 500 to 1,500 yen range depending on services, and there are usually lockers and a small rest area or sauna. It is easiest to reach by car and most facilities have on-site parking, while public transit may require a short walk, and try not to arrive right before closing.