You're right - lots of izakaya in that area are closed on Sundays - not just the smaller ones, but even many of the chain izakaya like Kaba and Tsukada Nojo. There are some okay places in the Atre complex on the east side of the station and the big office/shopping complex just past there.

There's a place called "The Zen" on the fourth floor of Atre that I like - good food and nice sake and shochu.

Maimon in the office complex is also pretty good for grilled meats.