The Nikkei average rose 0.7 percent by midday on Tuesday, helped by gains in auto makers such as Honda Motor Co. after the dollar scaled five-month peaks against the yen and oil prices retreated from record highs.
Other exporters such as office equipment maker Canon Inc. also climbed, but Fast Retailing Co., the operator of Uniqlo clothes shops, slid after its March sales plunged.
"The yen's weakness makes it easy to buy exporters, and we're seeing that especially with auto makers today," said Kazuhiro Takahashi, general manager of equity planning at Daiwa Securities SMBC Co.
The Nikkei finished the morning session up 0.66 percent or 77.57 points at 11,745.11, erasing losses made on Monday.
The broader TOPIX index was up 0.43 percent at 1,188.19.