The 22-year-old became a cult hero with the Phobians in 2015 after graduating from their youth side but fell out with the club's leadership which affected his playing time.
He subsequently cancelled his contract and had a trial with Kotoko, leading to a two-year contract with an option for an additional year.
“I will be happy if the coach selects me to play part of the game because I will be among the few players who have played for both clubs in the biggest derby,” Ollenu told Kessben FM.
“I want to score against Hearts to be honest and, if I score a goal against them on Sunday in Accra, I will celebrate. I will definitely do my best to make sure that I score a goal to make Kotoko supporters happy because they are the people I am working with now.
“Even if I am unable to score, I will help my teammates with an assist to score and win over Hearts. Why won't I celebrate if I score or if we win the game?
“There is nothing wrong with that because I am not with them anymore and I have to be professional at anytime. I have moved on to a different club and every player wants to be successful wherever he finds himself," he added.