The biwa (琵琶) is a Japanese short-necked fretted lute, often used in narrative storytelling. The biwa is the chosen instrument of Benten, goddess of music, eloquence, poetry, and education in Japanese Shinto.
The main point of differentiation between the biwa and the pipa (visually) is that the biwa has a bent neck, while the pipa has a straight neck, like an acoustic guitar.
This tag implicates lute_(instrument) (learn more).