【 判子 (はんこ)・hanko 】seal
In Japan, はんこ (also called 印鑑 いんかん inkan) are seals used in place of a signature for accepting, confirming, or acknowledging a package or document.
For this, when you receive a package in Japan, the delivery person will most likely say,
こちらにハンコをお願いします。
(kochirani hanko wo onegaishimasu)
Please sign (stamp) here.
Types of seals in Japan
There are different types of はんこ for personal or business, for casual and formal situations.