N5
ろうか
Definition
corridor, hallway, passageway
N4
けいさつ
Definition
police, police officer, police station
N3
はっけん
Definition
discovery, detection, finding
N2
ばいばい
Definition
trade, buying and selling, trafficking (e.g. of humans, arms, drugs), dealing
N1
しつ
Definition
room, wife (of someone of high rank), scabbard, Chinese "Encampment" constellation (one of the 28 mansions)