I've read this web novel around 5-6 years ago so my memories is extremely vague.
The general concept is this man (definitely not a teenager) whose age is around mid 20 to early 30 (also has a job, I think, not sure) gets summoned or got the ability to transport to another world ( only to 1 world) and also back to earth. The only event I remember from this novel is that he seems to have saved a lot of people (children I think) from the other world and had temporarily brought them to earth. Another event is some kind of contest/tournament of fight or something similar. In this contest, he and his sister(?) (he can bring people with him) had participated in it and they won the top spots (I think). He also travels to different regions in the other world to learn/gain magic to different elements (yes, magic exists). I don't remember what he does there to get the magic but he have to travel to each place for each magic element (fire, water, earth, etc). This part I'm not exactly sure (possible I mixed this part with other novel) but I think he also found some extraordinary creatures in earth too.
I think it was discontinued or something. In the web novel website I use, I remember it only having around 400 something chapters
If anybody has read this, can they tell me the name of this web novel.
Thank you
by TECH_MASTER_PC