四国 しこく艦隊 かんたい下関 しものせき砲撃 ほうげき事件 じけんでしょう
shikoku kantaishimono sekihōgekijikendeshō

Noun
Desu Copula

Expresses probability in a polite manner ("probably…") of 四国艦隊下関砲撃事件

1. Probably the Shimonoseki bombardment by the Four Nations Fleet.

Polite
Presumptive
Conjecture