Medium processing apparatus, image forming apparatus, and image forming system

A medium processing apparatus comprising:

• a liquid applier to apply liquid to a medium;
• a medium processing device to process a media bundle including the medium on which the liquid is applied by the liquid applier;
• a liquid storage to store the liquid to be supplied to the liquid applier;
• a liquid detector including a pair of electrodes to detect the liquid in the liquid storage;
• and
• circuitry configured to:
• control the medium processing apparatus to process the media bundle;
• repeat:
• application;
• and
• non-application of,
• a direct current voltage to the pair of electrodes of the liquid detector alternately at a regular interval to perform an intermittent application,
• to detect the liquid in the liquid storage by the liquid detector,
• wherein the circuitry is further configured to:
• perform the application of the direct current voltage to the liquid detector for a first period in the intermittent application;
• perform the non-application of the direct current voltage to the liquid detector for a second period in the intermittent application;
• and
• control a ratio of the first period to a sum of the first period and the second period to be equal to or less than a given ratio.