Caine is quite literally ready to help you take a load off your back in Eiyuden Chronicle: Hundred Heroes. When your team comes back to HQ with resources, they will be taken by Caine and applied to the HQ resources. He's organized and prepared to help you manage the materials your rebuild and town growth needs.
When you first see HQ as you get into Hoist the Alliance Banner, you will join Lian and the rest of your team in the Great Hall. Here you will meet a variety of characters brought in by Ymir to help with the growth of your HQ, Caine is recruited among them.
In the west corner of the first floor of the Castle HQ are two shop icons. One is Sumire ready to store your individual items. The other is Caine who will automatically take any items you found while adventuring that will help with HQ resources and store them for you. At his station, you can also sell these for HQ funds to go toward renovations.