I've been reading and rereading this series for quite some time but I only noticed today that Flan is calling Remi "Onee-tan". In the entire time I've been reading this, inside my head Flan refers to her as "Onee-sama".
Sis, don't sleep under the kotatsu!You'll catch a cold!Ah, I know!Arrrgh...Unf!SpopThat should do it!Shiver...Shudder...