If I'm understanding right, it's 'Why Musashi-chan doesn't come back from the beauty parlor', with that (エステルーム) being the name of one of the relaxation rooms in the Amazones.com event (which was still going when this was published). That room gave a bonus cooldown reduction for Summer Musashi but not the normal Saber one, so the spikey-updo Musashi seen here would take longer to recharge in it.