May 25 (Bloomberg) -- Japan’s Nikkei 225 Stock Average rose 121.19, or 1.3 percent, to 9,347 as of the close in Tokyo. The following were among the most active shares in the Japanese market today. Stock symbols are in parentheses after company names.

Defense-related stocks: North Korea said it conducted a “successful” nuclear test today, carrying out a threat made last month after the United Nations condemned the communist country’s ballistic missile launch.

Hosoya Pyro-Engineering Co. (4274 JQ), a maker of flare bombs and smoke candles, surged 18 percent to 530 yen, the highest since August 2007. Howa Machinery Ltd. (6203 JT), a maker of machine tools and firearms, jumped 9.1 percent to 60 yen. Ishikawa Seisakusho Ltd. (6208 JT), which makes weapons for the national defense force, soared 17 percent to 70 yen.

Home-appliance retailers: Best Denki Co. (8175 JT), Bic Camera Inc. (3048 JT), Kojima Co. (7513 JT) and other electronics retailers gained after the Nikkei newspaper reported over the weekend that sales of flat-panel televisions increased 45 percent during the first week of a government-led campaign to encourage consumers to buy environmentally friendly appliances. Nikkei cited survey company BCN Inc.

Best Denki jumped 17 percent to 412 yen, rising the most since April 2003. Bic Camera climbed 7.5 percent to 31,150 yen. Kojima surged 17 percent to 619 yen, the highest since November 2007. Edion Corp. (2730 JT) added 6.1 percent to 683 yen.

Steelmakers: Nippon Steel Corp. (5401 JT) and other steelmakers gained after the Nikkan Kogyo newspaper reported Toyota Motor Corp. (7203 JT) won’t seek further price cuts from Nippon Steel and other steelmakers after winning a 10 percent reduction last month. Nippon Steel rose 2.7 percent to 348 yen. JFE Holdings Inc. (5411 JT) advanced 3.7 percent to 2,970 yen. Kobe Steel Ltd. (5406 JT) rallied 4.4 percent to 166 yen. Toyota slid 0.3 percent to 3,560 yen.

Chiyoda Corp. (6366 JT) climbed 8.4 percent to 777 yen, the highest since Sept. 26. The plant-engineering company was raised to “buy” from “hold” by Toshiharu Morota, a Tokyo-based analyst at Deutsche Bank AG, while Nomura Holdings Inc. analyst Shigeki Okazaki lifted Chiyoda to “neutral” from “reduce.”

Daiichi Sankyo Co. (4568 JT) rose 4.2 percent to 1,748 yen. Ranbaxy Laboratories Ltd. (RBXY IN) Chief Executive Officer Malvinder Singh quit the company. Singh, 37, had been appointed chief executive for a five-year term in 2008 after Daiichi Sankyo, the third-biggest Japanese drugmaker, agreed to pay $5 billion for a majority stake in Ranbaxy. A joint statement from the two companies yesterday didn’t specify a reason for Singh’s departure.

Daiwabo Co. (3107 JT) and other makers of medical masks and materials fell after Japanese schools in Hyogo Prefecture, where the nation’s first confirmed case of swine flu in someone who hadn’t traveled abroad was detected, started to reopen as concern about the virus subsided. Neighboring Osaka Prefecture announced over the weekend it will resume classes in public schools on May 25. Daiwabo plunged 13 percent to 289 yen. Shikibo Ltd. (3109 JT) plummeted 19 percent to 155 yen. Unitika Ltd. (3103 JT) lost 4.2 percent to 91 yen.

Fujimori Kogyo Co. (7917 JT) surged by its daily limit of 14 percent to 818 yen, the highest since Oct. 3. The maker of plastic wrapping materials was rated “outperform” by Hidemitsu Umebayashi, an analyst at Daiwa Institute of Research.

Hitachi Construction Machinery Co. (6305 JT) added 2.1 percent to 1,516 yen, while Komatsu Ltd. (6301 JT) rose 2.6 percent to 1,360. The earthmover makers were raised to “buy” from “neutral” by Kei Nihonyanagi, a Tokyo-based analyst at Goldman, Sachs & Co.

Japan Communications Inc. (9424 JX) rallied by its upper limit of 12 percent to 90,100 yen, its highest since Sept. 3. The wireless-Internet provider today said it will conduct a 5- for-1 stock split.

Keihin Corp. (7251 JT) gained 9.1 percent to 1,150 yen. The maker of parts for cars, motorcycles and machinery was boosted to “strong buy” from “buy” by Takao Oshitari, an analyst at Mizuho Securities Co., while Nikko Citigroup Ltd. raised its rating on Keihin to “buy.”

Mitsui Sumitomo Insurance Co. (8725 JT) rose 3.7 percent to 2,805 yen. The insurer is in talks with Malaysia’s Hong Leong Financial Group Bhd. to work together on non-life insurance operations in Malaysia, Nikkei English News reported on May 23.

Nippon Felt Co. (3512 JT) rallied 6.9 percent to 420 yen. The felt maker said it will retire 10.71 percent of its outstanding shares on June 3.

Pacific Metals Co. (5541 JT) advanced 3.2 percent to 717 yen. The maker of stainless steel may generate about 80 percent of its sales revenue overseas in the year ending March 2010, marking a record figure on favorable demand in China, the Nikkei newspaper reported.

Pioneer Corp. (6773 JT) declined 3.9 percent to 274 yen. The Development Bank of Japan has started assessing Pioneer’s assets to see if the maker of car audio systems deserves public funds, the Nikkei newspaper said yesterday.

Shionogi & Co. (4507 JT) rallied 5.7 percent to 1,952 yen. The drugmaker will apply for approval to expand the uses for four drugs already in the U.S. market, aiming to boost their sales to 20 billion yen, Nikkei English News reported. Shionogi also aims to introduce a new influenza drug in Japan in 2010, Nikkei said in a separate report.

USC Corp. (9844 JT) rose 3.7 percent to 878 yen. Kyoshin Technosonic Co. (7574 JQ) added 1.1 percent to 375 yen. The companies said in a statement they reached an agreement to merge under a holding company on Oct. 1. USC will receive 1 share of the holding company for each USC share, while Kyoshin Technosonic will get 0.45 share for each of its shares.

To contact the reporters on this story: Norie Kuboyama in Tokyo at nkuboyama@bloomberg.net. Akiko Ikeda in Tokyo at iakiko@bloomberg.net;

Last Updated: May 25, 2009 02:40 EDT