The Tasuki (sash) is the most important thing in your event pack. It’s the item that must be passed from team member to team member around the course. This is effectively the “baton” in your relay. Any team that does not have its Tasuki on the course at any point during the event risks disqualification.
The beautiful satin tasuki is a great commemorative item from the event and is yours to keep. Maybe your team can award it to your team manager or best performer on the day – but put it through the wash first!