It turns out that $115 million can't buy a nickel's worth of common sense.

If it could, then the Japanese tycoon Genshiro Kawamoto wouldn't be sitting on nearly 20 vacant homes in Kahala, watching them slowly decay and making a mockery of his dubious "Kahala Avenue Mission" project.

He kicked off this fantasy last March, playing for the news media as he turned over three of his fancy houses to Hawaiian families, who now live in them rent-free.

They represented the beginning of his plan to turn Kahala Avenue into a "nostalgic Hawaiian street" — whatever that is. He would bring in more Native Hawaiian tenants, fill in the swimming pools and tear down walls separating his houses from the rest of the community. He would also put his art collection on display.

But except for those three families, Kawamoto's self-described philanthropy has so far proven to be a mirage.

His plans to bring in five more Hawaiian families have gotten nowhere.

His nostalgic Hawaiian street is just an eyesore, with crumbling graffiti-covered walls, tall weeds and unkempt trees, even a pool filled with stagnant water, a potential breeding ground for mosquitoes and other vermin.

And with the exception of a few Elvis-like sightings — there he is, trimming some hedges with garden shears — the billionaire has disappeared from the radar.

Of course, if an eccentric foreign real-estate speculator wants to buy up Hawai'i property — as Kawamoto did in the 1980s, snapping up about 160 homes on O'ahu and driving up real estate prices as he cruised through neighborhoods in his limousine, pointing out the houses he wanted — he has every right to do so.

But to call himself a philanthropist and expect people to believe him? Common sense says, not a chance.