The Sakura Bridge has an unusual 'X' shape, and it also has posts mounted on the outside of the bridge (on the downstream side). Perhaps the posts support a barrier for the big fireworks festival during the last Saturday in July.
I've noticed in more recent photos that a cone has been constructed where the arms (and legs) of the 'X' come together. The steel superstructure is supported on two single-column bents with hammer-head bent caps (and four ramped abutments).
Tokyo's River Crossings: Sakura Bridge by Mark Yashinsky is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 United States License.