P.O Box in Japan

I want to send a package to a friend who lives in Japan, but he does not have a p.o box.

Can I send my package just from his house address, or should I tell him to get one?

And if so, would anyone perhaps know how much it'd cost? I'm not sure if it differs by city/prefecture, but he lives in Ichinomiya, Aichi.

You can send it to his address. The shipping cost is determined by your local post, so ask them.

Usually, packages are sent to the home address of the recipient. Here in the US, if the mailbox is too small, then a note is placed in the mailbox informing the recipient they have a package at the nearest post office. I must admit I'm not 100% sure, but I don't see why it would be any different in Japan.

Getting a P.O. box in JP is extremely difficult unless registered large firmes such as Toyota or Nissan or schools/universities.
The cost of P.O box is free if JP Post accepts it.
There are some private firms run private P.O box business around 2,000 Yen per month.

If the receiver does not have a physical address in JP or not willing to receive at the address, you can send it to the nearest JP Post office or branch. JP Post office/branch will keep letters/parcels for up to 10 days with free of charge.

Everyone, you've all been very helpful! Thank you very much!!