Here's a vegan restaurant to the North East of Shinjuku (Tokyo) which offers non-meat versions of both classics.
http://www.showtennen.com
Lunch set for 900yen or there's a lunchtime buffet on Saturdays for 1,000yen
open 11:30 to 14:30 and 6pm to 10pm
Address Okubo 2-6-10 - nearest station, Shinokubo
MAP
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And a fair hike from Meguro Station
http://www.woodmoon.jp/ MAP