Idemitsu Kosan Co.'s plan to raise as much as ¥138.5 billion ($1.2 billion) by selling 48 million shares sent its stock on its biggest fall since 2008 on Tuesday. The refiner's move is the latest in the fight with its founding family over a merger with longtime rival Showa Shell Sekiyu K.K.
Here's a rundown of the issues behind one of Japan's most acrimonious business battles:
What has Idemitsu been trying to do?