Alternative form of 鳦 or 乙: swallow

Henan (a province of China; capital: Zhengzhou)

what number, how many (used with a counter) / (used with も) many (used with a counter)

Tainan

Funan, an ancient kingdom of Southeast Asia

one's second son

(historical) Syonan, Singapore (an island and city-state in Southeast Asia), as part of the Empire of Japan

difficult problem

obscurity

dense, abstract, abstruse, recondite