Flag created by CincyFlags for the neighborhood. 
Its symbolism, according to CincyFlags in [1]:
"The Music Hall Rose Window in the flag’s canton represents the vibrancy of OTR’s residents.
Two color blocks that represent the Miami &amp; Erie canal on bottom and the namesake of the neighborhood, the Rhine River, above.
Red for the vibrant community.
White for the Rhine, peace and harmony.

Blue for the canal and good fortune."
Own work using: https://www.cincyflags.com/otr
CincyFlags