This is an aesthetic addition by the early Biwa players of Japan, who use an even larger plectrum for their instrument. Though it’s cumbersome at first, the bachi (plectrum) allows the relaxed player to use the power of their whole arm to execute a solid, percussive strike with ease. The shamisen can also be played simply with your finger, guitar pick, or more!

https://youtu.be/jLvIbSISF8Y