Sullivan & Cromwell and Mori Hamada & Matsumoto have advised Japanese insurer Mitsui Sumitomo Insurance Co. Ltd. on a $1.3 billion hybrid notes issue on the Singapore Exchange.

MSI, Japan’s largest non-life insurance company by combined premiums, is offering the 60-year notes to raise funds for general corporate purposes. In a prospectus for the deal, the company said that recent disasters including flooding in Thailand and last year’s earthquake and tsunami in Fukushima had driven up reinsurance prices, forcing insurers to shore up their capital reserves.

Tokyo partner Izumi Akai led Sullivan & Cromwell’s team advising MSI on U.S. law. Mori Hamada partners Hideki Matsui, Toshifumi Ueda, and Yasuhiko Fujitsu were the issuer’s Japanese counsel. Both firms have advised MSI and its affiliated companies on previous deals, and were co-counsels on the insurer’s $6 billion merger with Aioi Insurance Co. Ltd. and Nissay Dowa General Insurance Co. Ltd. in 2010.

Simpson Thacher & Bartlett Tokyo partner Takahiro Saito headed a team advising the underwriters–led by Goldman Sachs International; J. P. Morgan Securities; Merrill Lynch, Pierce, Fenner & Smith, Inc.; and Nomura Securities International, Inc.–on U.S. law. Tokyo-based Nagashima Ohno & Tsunematsu provided Japanese law advice to the underwriters. The firm did not respond to a request for comment.

The deal follows a similar Singapore bond offering by MSI’s banking affiliate, Sumitomo Mitsui Banking Corp., in January. Simpson Thacher also advised the underwriters of that $1.5 billion deal.