Talismanic Japan forward Keisuke Honda and playmaker Shinji Kagawa were included by Nishino among a group of 27 players.
Nishino, who took over from Vahid Halilhodzic after the latter's firing last month, is scheduled to name his final 23-man World Cup squad on May 31.
"Of course I expect to pick the World Cup squad from these 27 players," Nishino said.
"Honda and Kagawa have been core players of the national team and I've called them up in the hope that they will be able to contribute."
Nishino called up 17 overseas-based players to face Ghana in Yokohama in Japan's final home FIFA World Cup warm-up.
Though Kagawa has been struggling with an ankle injury, Nishino wants to give the Borussia Dortmund player every chance to make the plane to Russia.
"Kagawa requires truly delicate thinking," admitted Nishino.
"We have high hopes for him, and want to make a final decision during this training camp. Without doubt he is a player who can't be replaced."
Leicester City striker Shinji Okazaki and Galatasaray full-back Yuto Nagatomo, who have both won over 100 caps, were also among those selected.
Japan have been drawn alongside Colombia, Poland and Senegal in Group H at the FIFA World Cup.
Honda's goals helped Japan reach the last 16 of the 2010 World Cup in South Africa but Japan crashed out of the 2014 Brazil tournament at the group stage.
Japan Squad
Goalkeepers: Eiji Kawashima (Football Club de Metz/France), Masaaki Higashiguchi (Gamba Osaka), Kosuke Nakamura (Kashiwa Reysol);
Defenders: Yuto Nagatomo (Galatasaray S.K./Turkey), Tomoaki Makino (Urawa Reds), Maya Yoshida (Southampton FC/England), Hiroki Sakai (Olympique de Marseille/France), Gotoku Sakai (Hamburger SV/Germany), Gen Shoji (Kashima Antlers), Wataru Endo (Urawa Red Diamonds), Naomichi Ueda (Kashima Antlers);
Midfielders: Makoto Hasebe (Eintracht Frankfurt/Germany), Toshihiro Aoyama (Sanfrecce Hiroshima), Keisuke Honda (CF Pachuca/Mexico), Takashi Inui (SD Eibar/Spain), Shinji Kagawa (Borussia Dortmund/Germany), Hotaru Yamaguchi (Cerezo Osaka), Genki Haraguchi (Fortuna Düsseldorf/Germany), Takashi Usami (Fortuna Düsseldorf/Germany), Gaku Shibasaki (Getafe C.F./Spain), Ryota Ohshima (Kawasaki Frontale), Kento Misao(Kashima Antlers), Yosuke Ideguchi (Cultural Leonesa/Spain);
Forwards: Shinji Okazaki (Leicester City Football Club/England), Yuya Osako (Werder Bremen/Germany), Yoshinori Muto (1.FSV Mainz 05/Germany), Takuma Asano (VfB Stuttgart/Germany).
Source: AFP
