Digging with Bingo was a side mission in Ōkami, taking place in Taka Pass. Amaterasu and Issun met Bingo, the Expert Exacavator, who was trying to find buried treasure with his pendulum, seemingly hidden beneath a pile of leaves. Amaterasu managed to use Galestorm to remove the leaves, leading to the her and Bingo to engage in the digging minigame to find the treasure.
This minigame is similar to that time with Mr. Bamboo in Sasa Sanctuary, except with the new additions of the Galestorm and Waterspout Celestial Brush techniques. Galestorm lets you pick up and sweep your partner (in this case Bingo) safely across one block, letting you skip across spikes and water. Waterspout can instead be used to lift Bingo out of water when he is caught in it, and then walk onto a row of blocks at a higher level.
Start the minigame and use Bloom to open the giant buds for some extra time, while taking Bingo across the first spiked block with Galestorm. And again across the second block once he has fallen down. You can safely fall down after this again and continue right past the first water pit, but must use Waterspout to reach a higher area at the second one, or alternatively cross the gap past it with Galestorm.
From here on you can essentially continue east unimpeded, making sure to use Bloom to gain more free time (and speed up Bingo as well). Once he reaches the far right corner he will start telling you to dig, which ends the mission, awarding you with a Sun Fragment, and Bingo with the knowledge that you were the true treasure all along.