OK, here is an ink that lovers of brown ink will take delight.
It's somewhat old hat now, but Sailor makes ink and pens. They are a Japanese company. They also have a master ink maker who blends custom inks for certain special shops in Japan carrying Sailor products. For a while, these inks were available with some diligence as these shops did not have international ordering on their web sites. But now however those days are gone with the rise of the "ink speculator" and the "jewel bottle shortage". Some shops now only sell to someone in person, and other popular ones are sold out within hours, while another has raised prices 50%. Accept my apologies for posting a review of an ink you may not be able to purchase anytime soon.
And I have further bad news for you, dear reader: this ink is a close match for Parker Penman Mocha.
So I am unsure if I should just always have a pen filled with this ink until the bottle is empty, then place it upon the shelf, and remember the good "inky times" we once had. Or whether I should save it, preserving it for the future. Alas, why wait for a future that may never come? It will be used.
With that introduction, the review. As typical for me, the papers used are Mohawk via Linen, Hammermill 28 lb Inkjet, and as long as this book has a blank page, Clairefontaine. As typical, these iPhone photos show the ink as darker than it really is. It is not black, but a dark brown. I'm not sure whether Sailor's Do-you is darker, it may well be.
Not sure how this will wash. An ink smear is a brown, but here some dirty red was showing up. Some experimentation would be in order.
The ink did not spread very much, but you can see a number of colors at the edges.