According to Nikkan Taishu, Yamaguchi Tatsuya will return to Johnny’s office to the last Tokio live concert before Nagase Tomoya departure. 

Seems the next april is the final for Tokio, Nagase Tomoya will leave the office and Tokio will disbanded. In regarding to farewell for fans, Tokio will be held a “last concert” and to do so Yamaguchi Tatsuya will join them. Also there are arrangements into Johnny’s office. 

The possibility is quite serious, Yamaguchi will be returned only once for Nagase's good-bye live.According to the article, it was the fact that Yamaguchi was reflected in "DASH" and "Kanjam" broadcast last month, and it seems that Johnny's is trying to carefully judge the reaction of the audience.