Farming Master of the Twin Blades on NG+ nets me around 400-500k Gold and 2.5-3k Glory (around 8 mins each run). I use the Glory to buy Kappa Shells and craft Saisetsu-shin Sake. Most of the gold comes from selling the gear dropped by revenants, so the sell mark up perk at the blacksmith is a must.
If you don’t need gold, spamming this mission on normal difficulty without killing revenants wiill grant 2 Saisetsu-shin sake each time.
500k Proficiency with Dual Swords is required to unlock this mission.
Here’s a video of one of my Amrita runs, where I make 80m in 5 minutes (16m per minute) in The Demon King Revealed. I believe this mission is slightly more efficient than The Ghosts of Sawayama, which is the next best option (and only option if you run out of Himorogi Branches)
Best Clan for Amrita Grinding – Toyotomi
Best Guardian – Suzaku (if you can keep near 100% LW Uptime)
Make sure to use the 25% Amrita Kodama Blessing while wearing a Kodama Bowl
My Amrita Bonuses
11.3% from enemies 38.7% Amrita Earned 88.7% Amrita Earned while using Living Weapon 9.2% from Yokai