To expand your inventory, you need an item called "Magic Backpack".

1. Talk to «Wandering Merchant Zyro» and accept the quest.

• Coordinates.
• Noria (186,109)
• Devias (226,52)
• Elveland (55,199)

• Quest «Magic Cloth» to expand the inventory of the 1. - You can get Magic Cloth from Silver Valkyrie at Atlans 3.
• Quest «Space Cloth» on the expansion of the inventory 2. - You can get Space Cloth from Alquamos at Icarus.

Use Magic backpack by clicking the right mouse button.
Then reconnect to the game «Switch Character».