Honda manual (sticker underside of bonnet) says the Jazz needs to be run for half hour every three months. We could all pick some holes in that statement. I would think if both batteries are fully charged it suggests one could leave it approaching three months.
The HV battery can last 3 months - possibly longer. The downside is if the HV battery is allowed to fully discharge by leaving it unattended for longer than this it can be damaged - and is VERY expensive to replace. You cant charge it at home other than running the car for 30 minutes every 3 months to charge and recycle the battery. (main dealers might have special high voltage chargers to maintain their stock, but its not a DIY option) I saw a 'handover ' video made by a Honda dealership which mentioned this but dismissed the possibility of a car being unused for 3 months as highly unlikely - But they live different lifestyles from some of us.
But the small 12 volt battery may run flat in well under 3 months. Modern cars have lots of electronic systems that remain constantly active, consuming quite a bit of 12 volt battery power. Its not just Honda. Its not such a disaster as the car can be jumped started from another car ,and there are precautions you can take to keep it charged. Regularly plugging in to a smart charger at home for instance. I once left the car unattended for about 8 weeks during January and February and it powered up and started ,no problem. I had left a solar powered battery charger plugged into the OBD ii port. Despite the short daylight hours and little sun this gave enough amps of charge to keep it topped up. . If the car is attended but not driven you can power up the car from time to time and even if the car is not driven it will charge the 12 volt battery during that time. But maybe not a long term solution because it would be drawing charge from the HV battery.
One further solution that might help if, for instance, the car is left for a long period in an airport car park. You can buy 'power bank ' jump starter packs,which are kept charged with a usb charger. They are small enough to keep in the glove box but claim to be able to provide enough amps for a short period to jump start a normal car starter Should be more than enough to power up a hybrid. Cost from about £30.