The Kesennuma City Memorial Museum occupies the former Koyo High School, south of the city centre on the coast. The school survived the 2011 tsunami badly damaged, and parts of the building have been left as they were, with wreckage, classrooms, and exhibits explaining the sequence of the disaster.
This is not an easy stop, and it should not be treated as a quick photo opportunity. Give it time. It is one of the strongest places in Kesennuma for understanding both the scale of the tsunami and the practical disaster education that followed.