Hon Choshi (base tuning)
Ni Agari (middle string raised)
San Sagari (thin string lowered)
Now, we can use the tuner to set the pitch of the other strings if we want to. If so, you can use the helpful chart below.
However, if you’re not playing with other instruments, it’s not actually necessary to play in a precise key!
The most important thing is the tonal spacing between the strings. No matter where the thickest string is tuned to, as long as tonal spacing is aligned, everything will sound great!
For example, let’s assume the ichi no ito is a bit flat of C, as long as the other strings are flat by the same amount, the strings will still be in tune with each other and so the shamisen will sound good.