E-commerce conglomerate Rakuten Group is extending a three-month rally in credit markets as it unveils fundraising plans including listing a unit.

But lingering questions whether it will be able to service looming debt maturities are crimping that rebound and leaving it stuck as Japan’s riskiest major borrower.

Euro and dollar bonds from the company — a household name in Japan — have jumped from record lows of about 40% to 60% of face value in July to 61% to 71%, after announcing a planned listing of unit Rakuten Securities Holdings. Some of those prices are still in distressed territory though on concern that its unprofitable mobile business will pressure finances. Its credit-default swaps, which insure against debt nonpayment, remain the highest in Japan at 553 basis points, CMA data show.