Ah! My Goddess Season 1 Episode 9 Ah! The Secret of the Queen and the Goddess.

Keiichi and Belldandy go on a date to the amusement park. While there, Belldandy accidentally reveals her true identity as a goddess to Keiichi's senpai, Tamiya, who promises to keep it a secret. However, Tamiya's girlfriend, Otaki, overhears the conversation and tells their professor, Marller, who is actually a demon in disguise. Marller then hatches a plan to steal the goddess wings from Belldandy, which will allow her to become queen of Hell. Meanwhile, Belldandy's sisters, Urd and Skuld, arrive on Earth and get involved in the chaos. As the plot thickens, Keiichi and Belldandy must find a way to stop Marller's evil scheme and protect their relationship.