BUR #5982 has been approved by @evazion.
create implication senjou_no_valkyria_4 -> senjou_no_valkyria
create alias senjou_no_valkyria -> senjou_no_valkyria_(series)
remove alias valkyria_chronicles -> senjou_no_valkyria
create alias valkyria_chronicles_(series) -> senjou_no_valkyria_(series)
Subseries. Also renaming the main tag because someone might think it's about the first game.