deliver, reach, arrive, report, notify, forward
届 centers on something reaching its intended destination: delivering an item, a message arriving, or a report being forwarded to the right person.
届 combines 尸 (a body or person) with 由 (origin or reason), suggesting a person arriving at a destination or a reason being conveyed. The exact historical development is uncertain, but the modern form visually supports the idea of delivery or arrival.
Picture a person (尸) carrying a package with a clear reason (由) for delivery. The package reaches the recipient: 届 means deliver or arrive.
For カイ, imagine a delivery person shouting 'Coming!' as they arrive: 'Coming' sounds like カイ, and the package is delivered.
to reach; to touch; to get to; to carry (of sound)
to deliver; to forward; to send
report; notification; registration
report; notification
to make sure of; to ascertain; to see with one's own eyes; to watch to the end; to watch to make sure (that)
to send (a person or thing) to; to deliver; to escort
outrageous; reprehensible; rude; insolent; nefarious
to report; to notify
destination (of a letter, parcel, etc.); receiver's address; consignee
to be scrupulous; to be attentive; to be prudent; to be complete; to be thorough
negligence; carelessness; incompetence; mismanagement
delivery (of a package, goods, etc.)
estimated delivery date
destination (of a letter, parcel, etc.); receiver's address; consignee
deliverer; delivery guy
delivered (of a package, etc.); delivery completed
to be extremely thorough, focusing on even the finest of details
notice of absence; form requesting post office to hold mail during an extended absence
very rude; very insolent; extremely reprehensible; outrageous
rude person; villain; blackguard; scoundrel; rogue; libertine