Liar. Though usotsuki can be a strong word, usotsuki can have much less severe connotations than the English word, frequently used without much seriousness.

Song.

To sing.

A Japanese short sword; similar in construction to a Katana, but shorder (usually around 40cm). These were carried as a secondary weapon by Samurai.

Crocodile; alligator.

We. Wareware is a very stiff, official-sounding form of we. It is usually used by members of an organization to describe their group officially. In anime, most often used by officious villians talking about whatever evil group they're part of.

I; me. Masculine pronoun, used almost exclusively by older men.

I; me. Gender neutral, polite pronoun, widely used.

The dark; darkness. This can be used both literally and in a similar figurative sense to the English word, covering both shady or illegal activities, and evil things.

Guy; jerk. This crude word for another person is frequenly used as a relatively mild insult, either directly or when talking about a disliked person. "Kono yarou!" = "You bastard!"; "Ano yarou." = "That bastard."

Vegetables (food).

Guy; dude; fellow. A crude word for another person, used either in rough colloquial language or as a disrespectful way to identify another. Somewhat less insulting than yarou.

Four

Monster; ghost; specter; spirit; demon. Youkai is broader than any of the possible English translations, covering both physical and spectral supernatural creatures.

Ghost; spirit; specter. Yuurei is specifically used to describe the restless souls of the dead.