South Korea uses round, two-pin plugs. On the other hand, Japan typically uses Type A plugs, which have a different shape, so you'll need a conversion adapter. However, depending on the type of conversion adapter, problems can occur, such as poor compatibility with the outlet, making the plug "easy to pull out" or "not going in all the way and wobbling." This product is a support adapter designed to solve these problems. It creates a moderate fit between the conversion adapter and the South Korean outlet, allowing for a stable power supply. ※ This product is only for support. ※ The effect may vary depending on the individual differences of your conversion adapter and outlet. ※ Since we cannot confirm actual use in Japan, we cannot guarantee the usability or compatibility. Please understand this before purchasing. Shape: Round pins (4.8mm diameter) Color: Black Compatible Types: Compatible with South Korean C and F type outlets Quantity: Set of 2