A spat is rocking one of Japan's most popular Internet companies after the founder moved to kick out the board, enraging staff and sending shares tumbling.

Akimitsu Sano, who owns 44 percent of Cookpad Inc., shocked investors in January by calling on them to dump all other directors of the recipe-sharing site, saying the company was neglecting its main business. The stock fell 23 percent in one day and has whipsawed with each new skirmish in a battle to control a firm with more than 85 million monthly website users.

Facing exile, as Sano's stake in effect meant he could unilaterally replace them, the then board sought to negotiate a compromise, and by February reached an agreement for some members to retain roles. Nine directors — Sano, five of his picks and three others from the previous board — were anointed by shareholders at the annual meeting in March.