For about a decade, Isekai animes have been flooding the genre. We list 5 animes that were Isekai even before the Isekai boom. You just might not have noticed it. 

What is an Isekai? In this list, we defined every anime as Isekai in which a character from the real world is transported to a fantasy world or a parallel universe. It does not necessarily have to be reborn, but rather find a way there in some form. The real body does not exist anymore when visiting the parallel universe in the real world.

Although Sword Art Online technically does not count as an Isekai for many fans, the anime triggered a wave of further Isekai animes. These include, for example, Overlord, Konosuba, Re:Zero or That Time I Got Reincarnated as a Slime. 

MeinMMO lists five series that came out well before Sword Art Online and that you might not have realized were actually already Isekai. 

Inu Yasha – A girl lands in the world of a dog demon

• Japanese title: Sengoku Otogizōshi InuYasha
• First release in Japan: October 2000
• First release in Germany: April 2003
• Episodes: 167

What is it about? 15-year-old Kagome falls into the old well of her family shrine on her birthday. There she lands in historical Japan during the Sengoku period and meets the half-demon Inuyasha, who is bound to a tree. 

After freeing him, she sets off with him in search of the shards of a powerful magical jewel. The shards are being collected and used by evil demons to strengthen themselves and commit more misdeeds. 

Why is this an Isekai? Kagome travels through the portal, namely the well, to a completely different world. Although it is historically the past, the era operates differently from the real world due to the presence of magic and demons. It is, therefore, a true fantasy parallel world.