something you might like to know
Ichigo's name refers to Ichi and Go, meaning guardian angel or number one guard(literal translation). The word "Ichigo" in Japanese means strawberry but that is not its intended meaning in the anime.
Also by the fact that Aizen's Butterfly form has twelve wings. You can tell he is playing the part of Lucifer(The only twelve winged cherub/archangel in heaven) while Ichigo is playing the part of Samael/The angel of death.
Ichigo is denying Aizen entrance into heaven.