How about a sequel of Your Lie in April in the style of Rurouni Kenshin: Reflection? It'll be about an ex-pianist Kousei Arima who wakes up one afternoon to find himself lying on a prison bed. After escaping from the jail, he soon discovers that he was arrested by Kaori's parents during Kaori's funeral.
The culprits behind this act are Kaori's parents who aim for 7 dragon balls by creating a robot girl to replace their deceased daughter. So, Kousei decides to collect the 7 dragon balls with the helps of Jacob Marley & the ghosts of christmas.