How it works
A stock exchange has set trading hours (see related page), and trading through the exchange is not possible outside that time. In Japan, using a PTS (proprietary trading system, see related page) operated by a securities firm can allow stocks to be traded outside regular trading hours, such as early in the morning or in the evening.
Points to keep in mind
The stocks available, trading hours, and fees for after-hours trading vary by securities firm, and orders can also be harder to fill (lower liquidity) compared with trading on the exchange. Please check the conditions offered by the securities firm you plan to use in advance.