Whisk 1/4 cup poppy seed dressing, 2 tablespoons wasabi peas, and 1 teaspoon sesame seeds in a large glass or ceramic bowl; add chicken and toss to evenly coat. Cover the bowl with plastic wrap, and marinate in the refrigerator, about 1 hour.
Preheat an outdoor grill for medium-high heat and lightly oil the grate.
Place lettuce in a salad bowl; add pear, cranberries, remaining 2 tablespoons wasabi peas, and remaining 1 teaspoon sesame seeds.
Remove chicken from the marinade, and shake off excess. Discard the remaining marinade.
Cook chicken on the grill until no longer pink in the center and the juices run clear, 5 to 10 minutes per side. An instant-read thermometer inserted into the center should read at least 165 degrees F (74 degrees C). Cool chicken slightly and slice.
Pour remaining 1/4 cup poppy seed dressing over lettuce mixture; toss to coat. Top salad with sliced chicken.