Lukaku will look to add to his group-stage tally of four goals against a Japan defense conceding more than a goal per game.
Brazil will take on Belgium in Kazan on Friday at 9pm local time after France's clash with Uruguay. "I think there should be space for us behind the wings, or somewhere in that general area", said Inui after Saturday's training session.
"It's a new challenge for us to get through and hopefully we will make a new history for Japanese football".
Japan, on the other hand, have seen their national team play consistently at World Cup level for some two decades, but have never been able to go on a deep run at a major tournament like the World Cup.
Belgium's nine goals - scored in big wins over Panama and Tunisia, and a 1-0 victory over England in their final preliminary match - saw them top Group G and set up a meeting with Japan, who squeaked into the round of 16 thanks to FIFA's fair play rules.
"I'm asked this question nearly every single day, in terms of a penalty shoot-out, of course, it's something that I need to decide", he said of the likely order of takers.
"The ones who played against England are desperate to contribute again and those who were rested want to get out on the pitch". The semifinal would seem like a decent upgrade on the quarterfinals of the last World Cup and Euros and so far they started well.
"In essence they are exactly the same, great energy, organised".
Belgium defeated Japan 1-0 in a friendly in November, but Akira Nishino has since replaced the sacked Vahid Halilhodzic at the helm of the team.
Nonetheless, for all the love Belgium have gotten in recent years, they have advanced beyond the quarterfinals only once - and that was back in 1986. Keisuke Honda became Japan's first player to score at three World Cup's and he could be vital coming off the bench if Japan manage to stretch the game. Given that no African team qualified either, it means they are still in position to reclaim their status as lovable underdogs. They know what it takes to win a game of this calibre.
"We have a lot of respect for this team, and we don't think we are going to win this one easily".
So far, this year's vintage is doing its best to put that image to bed, with Eden Hazard and Romelu Lukaku leading a side that now has veteran poise and a steely ruthlessness along with its considerable talent. "Japan are a different team to Wales, we'll learn the lessons".