In summer i recommend bringing a hat or a parasol. Summer in japan is really hot and humid except hokkaido and highlands in honshu. Sometimes it is cold in june as you want a thin. In winter wear sturdy, waterproof boots, gloves, a winter hat and an insulated winter coat. If traveling in the winter, take an overcoat, gloves, scarf and earmuffs. You won't see many. It is calmer in the north part of japan such as hokkaido and tohoku region and much hotter in the south like okinawa and kyushu region. Average temperature in tokyo:. If you stick to tokyo, hiroshima and larger cities during your stay, you may dress more casually. Although during japan's rainy season (also from the beginning.