The 840P was manufactured by Panasonic Mobile Communications for Softbank Mobile. It was launched to support Softbank’s 3G W-CDMA network.
The phone was branded as a “Color Life” device due to the wide range of colour variants that were offered, as seen in the original marketing below.
There was also a variant of the handset for business users known as the Softbank as 840Pe. This included a "Keitai Function Control" that allows a company’s IT administrator to restrict certain capabilities including the camera, some communication capabilities and the ability save data to a memory card. This business variant was identical to the standard 840P but was only available in two colour variants, black and white.
The user guide for this model can be found
here.