Rinse rice under cool water until water is no longer cloudy and runs clear. Combine rice and water in a covered saucepan and bring to a boil. Cover, reduce heat to low, and simmer until tender, about 15 minutes.

Mix vinegar, sugar, and salt together in a saucepan over medium heat until sugar dissolves. Remove from the heat and let cool.

Combine softened cream cheese and mayonnaise in a blender; process until creamy.

Transfer cooked rice to a large mixing bowl. Sprinkle 1/2 of the vinegar sauce over the hot rice; mix gently. Taste and add more vinegar sauce if desired.

Empty 1/2 of the cooked rice into a springform pan; press down gently to fill the bottom of the pan.

Spread 1/2 of the cream cheese-mayonnaise mixture on top of the rice in the pan.

Layer crabmeat, cucumber, avocado, and cold cream cheese over top, in that order.

Spread remaining cream cheese-mayonnaise mixture over top. Empty remaining rice into the pan and press downwards until layers are firmly packed.

Garnish with sesame seeds. Place in the refrigerator for at least 2 hours before serving.