Lovely green 3Rensho on display, looks to also have the cable guides on the lateral…as bulgie indicated, looks to be routing for a third brake, an inverted sidepull. Two cable brake levers, Mafac or DiaCompe, aren’t hard to find and putting a brake like that would look cool…and seeing the green display bike, I would be inclined to go more period-correct… but not my bike nor my money.