InuYasha Episode 162: Forever with Lord Sesshomaru
Episode 162 of 167 of InuYasha, aired August 9, 2004, 24 minutes. Available with English subtitles and dub where released.
Episode summary
Rin has her doubts about whether or not she will be with Sesshomaru forever, after Jaken tells her that he and Sesshomaru will probably live longer than her, because she's mortal and they're demons.