Damn. I knew I had forgotten something ...
So sorry for not providing timely ideas, but I see that you are getting the best anyway 
In case you are not are not having an overly full schedule already, there would be three things you might want to consider:
1) "Omoide Yokocho" - a narrow, but very long street full of room-sized Japanese eateries: very local, very intimate. Yakitori, intestines, kushikatsu ... all good drinking food and to be consumed with copious amouns of shochu highballs or beer. If you cant decide, go to "Ucchan 25" (https://s.tabelog.com/tokyo/A1304/A130401/13059673/top_amp/), and have the tongue sashimi, the giblet skewers or the motsunabe. They recently put out a homepage of the association (Shinjuku-omoide.com).
2) "Sekishin Tei" (www.newotani.co.jp/en/tokyo/restaurant/sekishin/) at the New Otani hotel has a fantastic Teppanyaki lunchset (~6000 JPY for the basic one). Wagyu, Ise ebi, hotate ... At night not affordable. The food is great, but the view over the garden is fantastic (www.newotani.co.jp/en/tokyo/garden/).
3) "Ebisu Yokocho" - similar to #1, but actually indoors (https://favy-jp.com/topics/1144). Very good for heavy drinking at night with izakaya-style food. The oden shop is great, and just right for the current temperatures. Make sure you do the salary man thing and buy a "one cup" sake at the Lawsons before heading to the subway ...
If any specific question, please let me know (will be faster this time) 
Have fun ... I still have to wait three weeks for my next (business) trip to Tokyo.
Itadakimasu !
