I’m sorry, but I wasn’t able to find specific information on a video game titled “Toshi Tens? Keikaku: Eternal City” developed by naxat Co., Ltd. in the year 1991. It’s possible that the game did not achieve significant recognition or that it belongs to a niche category with limited available data. If you have any more details or if there are other games you’re interested in, feel free to let me know!