Line a baking sheet with parchment paper or a Silpat, and spread the chickpeas onto the sheet in a single layer. Bake for 35 minutes. Remove from the oven, set aside, and reduce the oven temp to 200F.
When the chickpeas are done baking at 400F, whisk the chickpea liquid with a fork in a large bowl until it becomes foamy. Add chickpeas and toss to coat with the whipped chickpea liquid, then drain off the excess liquid in a colander.
Stir together wasabi powder, salt, sugar, and cornstarch in a small bowl.
Transfer the chickpeas back to the large bowl, and toss to coat with the wasabi mixture.
Spread chickpeas on baking sheet in a single layer, and bake for 20 more minutes.