Murakami's fund City Index Eleventh will increase its stake in JAG to 58.96% from 15.35%, the filing said on Saturday, bringing the total holdings to about 75% when combined with shares held by parties related to the fund.

City Index Eleventh began building a stake in JAG while Carlyle Group teamed up with JAG chairman and CEO Tetsuo Yamashita in a proposed management buyout in November. Carlyle withdrew in February after City Index Eleventh offered a higher bid to buy the rest of the shares.

Murakami is one of Japan's few, well-known activist shareholders. His typical strategy includes building up a stake in a company in the middle of a takeover and demanding that management boost its sale price.

(Reporting by Makiko Yamazaki; Editing by Raju Gopalakrishnan)