Okay, this is what I know. It's not "Isekai Mahou wa Okureteru" but it's similar. Also, it's not "the Summoner" either. Two friends are summoned and one of them is a hero while the other (the MC) is just regarded as 'useless' but really he's a mage from our world but the 'hero' doesn't know that. Apparently the MC's a very talented mage in our world. Later into the series, the MC's family freak out about his disappearance. The MC's sister comes to the fantasy world by being summoned by another kingdom as a hero. The king(?) shows the MC and hero the MC's sis fighting in a coliseum to show her power. The MC becomes mad and threatens the other king to relieve his sis of her duties of hero...I think. I remember he threatens the king to keep his sis safe but I forget. This is later in the series btw. Additional facts are that the MC and his sister both have spirits they summon. The MC has a better spirit than the lil sis. Please help!!

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wanna know what it is so badly!!!

i'm interested in this too, but searches only bring up Isekai Mahou wa Okureteru! (Novel) and Souen no Historia (Novel), so it might not be added on this site, or it doesn't have Magic or Magician/s categories added to it's page

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stupid photobucket, wanting $400/yr just to display your images

Thank you for posting!!

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wanna know what it is so badly!!!

trying to get this noticed so I can fond the novel as well

Not sure about the sister part, but if the MCs are named Taichi and Kanade, then it's Isekai Cheat Magician. Feed this link through Google translate to take a peak in English: http://ncode.syosetu.com/n7500bd/

Thank you! I'll check if this is it.

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wanna know what it is so badly!!!