This RX-0 Unicorn Gundam Two-Way Waist Bag gives you the most flexibility. Hang it on the belt when you don't feel like wearing it. For those days when a crossbody is just too much, bring the separated pouch instead.
Specification‧3 compartments in total
‧Removable pouch bag
Size: 20W x 14H x 12D cm / 3.36L