Even if the hotel thing isn't shady, it'd tie up a lot of her father's assets. It's 1990 now, this is about to fall (as referenced in the first chapter) and will wipe out a lot: https://en.wikipedia.org/wiki/Japanese_asset_price_bubble
Given the market has already seen a drop, this could be a genuine courting of an investor to save the project. But the cracks were already apparent, and if "Take-sama" were smart, dangling bait like that could wipe out a source of funding to his mentor and possible rival. Lot of "ifs", though. If he's young and inexperienced and working off what his sensei is saying because he thinks it's a good investment... it's the same outcome.
Crucially, the prices for real-estate only dropped in Tokyo first, while outside of that region (including Kansai) they continued to rise or stayed the same. The bubble will finally be declared in '93, which could have been the OTL prompt for Ninomiya-san to, ahem, "make himself taller".