A twelve-piece box looks like a lot for one person. It is — which is why it works better split three ways.
Desk drawer
Keep the individually wrapped pieces at work and portion them out. Two pieces at 3pm beats a whole bag at 5pm, and the wrappers keep everything fresh for weeks.
Host gift
Add a handwritten card and the box becomes something you can hand over without a plastic bag in sight. It reads as thought rather than expense.
Movie night tray
Empty the box onto a tray or a flat plate, keep the sweet and salty sides apart, and put the tray on the coffee table. Presentation is most of the pleasure.
Storage note
Check the expiry date on each wrapper as you open the box and move anything close to date to the front. Mochi keeps best cool and sealed.