godan verb (-mu), transitive verb
be deep in conversation; get absorbed in talking
Describes a state where people become so engrossed in talking that they lose track of time or their surroundings.
友人と夜遅くまで話し込んでしまった。
I ended up talking deep into the night with a friend.
カフェで隣の席の二人がずっと話し込
The two people at the next table in the café have been deep in conversation for a long time.