Crunchyroll's Tower of God saw an unexpected appearance by Lero-ro on a poster in Episode 3 endorsing a beverage called "Banana Black," and the anime's official twitter account also pointed this out in a tweet in honor of National Banana Day.
Seeing the Ranker being a poster boy for the fictional product is definitely amusing, but could this have deeper implications? Given how Tower of God has developed a penchant for arousing curiosity about its world, it wouldn't be surprising if something so seemingly insignificant turns out to be further connected to the tower's mysteries. Here's some speculation about the "Banana Black" beverage and its inclusion in the anime.
The beverage is obviously banana-flavored and is shown available in three different sizes: a can and two sizes in bottle form. It looks like an energy drink, aside from the presumably canned coffee, and has a clear distinction between its labels "Banana Black" and "Banana Black HARD." While the difference could just be in taste, what if the "HARD" label indicates something more?
There is the possibility that whoever drinks the "HARD" beverage might experience more difficulties within the tower. The Rankers present themselves as knowing more than they let on, particularly Lero-ro. Since his face is on the posters, this could be his way of deceiving all the teams in the form of a refreshing beverage.
The number of bananas on each label could also mean something in regards to receiving advantages or disadvantages. Much like how Bam and Khun received a hint for Yu Han Sung's door test, perhaps the number of hints they're given for a future test will be decided by which Banana Black drink they consumed earlier. Similarly, a different test might have the teams fight again, but with each team given a certain amount of "lives" based on the total number of bananas on the labels for which drinks they had.
The most reasonable, yet boring, conclusion would be that the vending machine was only added to give the characters something to do. It provided the brief moment of Shibisu using "money mode" where he forms the OK hand gesture to pay for the drink. Having him make small talk with Bam while buying the beverage is also more engaging than if he were to simply approach him.
Another reason for the drink's inclusion could be to showcase a staple in Japanese culture: vending machines. With the anime being based on a Korean webtoon, perhaps the production team wanted to inject some Japanese charm into the show. It could also be some fanservice for Rak since he loves bananas. However, until the creators say otherwise, Banana Black could still play a more significant role in the anime.
