Have you unlocked Kurenai for Custom Deliveries or are you only refering to her questline about Shisui?

If you've unlocked Custom Deliveries, Sanana will be standing right next to Kurenai in Tamamizu (at 28.4/15.4).

If you havent unlocked Kurenai as a Custom Delivery option (or are trying to do that), you'll need to head to Kugane and speak to Kojin Hireling in Kugane (X: 10.1 Y: 9.9) to begin The Seaweed Is Always Greener (thats the quest that unlocks Kurenai as a Custom delivery option and Sanana as a vendor). You'll need to unlock M'naago in Rhalgrs Reach for Custom Delivery before you can unlock Kurenai - so if the Kojin isnt showing up, that could be a reason.