Property Management For Empty Mansion

Is there a service that can take care of a vacant mansion in Tokyo? We will be away for extended periods of time (1-4 months) overseas and would like to have someone check in once or twice a month, collect mail and forward it to us in packets which will provide that just need to be mailed at the post office. Most property management arrangements involve a percentage of rent but in our case we are just looking for someone to check in, air out, run water through the drains, etc. on a time and materials basis. We are willing to pay for this service on an hourly+expenses or a fixed fee. We just prefer to have a reputable firm to do this incase leak repairs or other incidents might need attention. It is owned outright so no issues with banks or mortgage companies.