I had heard some good things about Casa Tequila Tokyo in Shinjuku, but I have to say I was underwhelmed.
They have self-billed themselves as having the best nachos in Tokyo-far from it. The salsa was too sweet and there wasn't enough cheese (see above). This is a medium sized portion priced at ¥680.
They have corn tortillas for the tacos, but they are tiny, ¥300 a piece. I wouldn't go back.