noun
all talk and no action; mere sloganeering; starting with a bang but ending with a whimper
Describes a situation where there is a lot of initial enthusiasm, shouting, or promises, but no follow-through or concrete results. Often used critically of plans, campaigns, or people who are loud but ineffective.
彼の改革案は掛け声倒れに終わった。
His reform plan ended up as mere sloganeering.
掛け声倒れにならないように、具体的な行動計画が必要だ。
To avoid it being all talk and no action, we need a concrete action plan.
Compound of 掛け声 (shout, call) and 倒れ (falling, collapsing), literally 'shout-collapse', implying that the initial loud call ends in failure.