Ohio Rev. Code § 503.31
Where a remnant of a township in which there are no resident freeholders is located entirely within the boundaries of a municipal corporation, such remnant shall be considered a part of such municipal corporation as though it had been annexed thereto for all purposes except the exercise of eminent domain as to said annexed area. In every such case, the clerk of council or village clerk shall prepare a description of the remnant and an accurate plat thereof, together with his certificate that the description and plat are correct, that the area is a remnant of a township now defunct, and that it lies entirely within the boundaries of the municipal corporation. One copy of such description, plat, and certificate shall be filed for record with the county recorder and one copy with the secretary of state. The procedure shall be the same as in the case of the filing of annexation transcripts.
R.C. § 503.31