The cone referenced is
Yoyogi-koen, as hinted at in the hint. This is in the bottom-left quadrant of the map along the green (Chiyoda) line, just above Shibuya, which is in large, bold text. Harajuku is nearby (to the right of Yoyogi).
Take two stations east along the
green (Chiyoda) line to Omote-sando, which is a station containing both the green (Chiyoda) and purple (Hanzomon) lines.
Two more stationsContinue along the purple (Hanzomon) line, one north-ish, one southeast-ish until
you reach the Hanzomon station, the only station to solely carry the purple (Hanzomon) line.
From there, and you're at
One station north (To Kudanshila) and one station southeast (along the light blue Tozai line, per your hint) leads us to the NagatachoTakebashi station, the final answerstation.