Start left and below Toto, where the buttress turns the corner, on the right side of the arete where there is one very low bolt. Climb up and left to the left side of the arete on lichen ridden dirty (and possibly loose) rock and small cracks. Continue climbing just left of the arete through more somewhat dirty and loose rock to a grassy ledge. Above here the route becomes much cleaner and better. Climb up the slab/face just left of the arete into the start of the diagonal corner. Climb directly up from the base of the diagonal corner and over a bulge/small roof (harder), or go up the diagonal corner and move right (easier), to a large and flat granite ledge with anchor station.
From here you can continue up pitches 2 & 3 of the Diamond's Unknown 5.9 into Toto.