You agreed with the Hashira to go out to the beach, and after you get ready, you went to the beach and you found all the Hashira there

muichiro: builds a castle out of sand

Tengen: talking with renguko in the sea

Renguko: talking with tengen in the sea

Gyomei: prays while sitting in the sand

Sanemi: splash the water at giyuu

Shinobu: teasing giyuu

Giyuu: gets splashed and teasing

Mitsuri: playing in the sea

Obanai: in the sea, watching mitsuri