>>1803591> Yagan Line was planned in the steam age to form a Yagan-u Line to connect Ou Main Line directly, parallel to Touhoku Main Line. It and Nichhu Line (northward to Yonezawa) were not completed by JNR, with the former's southern side supplanted by Tobu. Adding onto this, the original plan was from 1927 for a railway between Aizuwakamatsu~Tajima~Imaichi.
> 政府は山形縣米澤より日中を經福島縣喜多方に至る鐵道、會津若松より田島を經栃木縣今市に至る鐵道及栃木縣鹿沼より栃木を經茨城縣古河に至る鐵道を速成し以て運輸交通の發達を促進せられむことを望むhttps://teikokugikai-i.ndl.go.jp/simple/detail?minId=005213242X03219270325&spkNum=0#s0Given how much of a money pit freight was compared to passenger rail, and JNR's debt crisis, it doesn't surprise me that this plan didn't come to pass.
Aizu Bus also has frequent shuttle service to Aizuwakamatsu from Koriyama (Tohoku Shinkansen), Shinjuku bus terminal and Haneda Airport.