One of our prime or classical guitars
Prime? That's only a term for the classical guitar, but within the context of the Niibori orchestra.
Or - if you're from the USA, "classic guitar"...
The classical guitar is usually 650mm long from nut to bridge, so it's the second smallest instrument in our guitar orchestra.
Everyone in hago plays classical guitar in some of our pieces; not all our repertoire uses 4 sizes of guitar.
That's perfectly natural of course - with a compass closely aligned to the human voice, the prime guitar alone is a natural choice for some of our quieter pieces.
The fact that we don't always use all our different guitars is for precisely the same reason that no symphony orchestra would dream of enhancing a quiet moment in the strings with 6 trombones...