Talk:Papa no Iu Koto o Kikinasai!:Volume 4 Chapter 1
Just to clear something about the "Takanashi's" grammar...
Takanashi=one of the Takanashi family, can also be used like "Takanashi-san" or the like
Takanashi's=possessive of one Takanshi
Takanashis=more than one Takanashi
Takanashis's=possessive of more than one Takanashi
If the family name was "Takanashis" instead of "Takanashi", then the singular possessive form would be "Takanashis'", plurar would be "Takanashises" and plural possessive would be "Takanashises'".