The sister of Martyn Hett, who was killed in the Manchester Arena bombing, has achieved phenomenal GCSE results after sitting her exams the day after discovering her brother had died. 。

SEE ALSO:Mariah Carey's moving tribute to fan who died in Manchester attack。

Martyn's brother Dan tweeted that his 16-year-old sister Nikita sat several exams the day after discovering her brother Martyn had died in the Manchester Arena attack in May. Nikita has just found out she got 11 A* grades for her GCSEs; the highest possible grades awarded for these exams.。

Here's a photo of Martyn (left) with Nikita (middle) and their sister Louise (right):。

Here's a photo of Martyn (left) with Nikita (middle) and their sister Louise (right):
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In a tearjerking Twitter thread, Dan has praised Nikita's strength and bravery when she sat those exams during the family's very dark time, calling her "an actual hero" and the "toughest person" he's ever met.。

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"I didn't even know what day it was at that point, it had been such a horrific few days," Dan added. He relays seeing his sister that morning getting ready to go to school to take her GCSE exams. 。

Tweet may have been deleted。Dan says that Nikita was told she didn't need to sit the exams, and they'd use her predicted grades given the circumstances. "Nik said: nope! and took the lot," wrote Dan.。Mashable Top StoriesStay connected with the hottest stories of the day and the latest entertainment news.Sign up for Mashable's Top Stories newsletter。

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"It was hands-down the toughest shit I have ever seen. Sleeves rolled up, get it done," wrote Dan.。

Nikita got her results on Thursday morning, and discovered she aced her exams. Dan expressed his pride at his sister's incredible achievement under such tragic circumstances.。 Tweet may have been deleted
 。Tweet may have been deleted。

Dan added that his "kid sister" is "the toughest person" he'd ever met. "Don't mess with her. Be inspired!" 。

Nikita told
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BuzzFeed News 。

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that focusing on her exams were a way of coping with her brother's passing. "I'm good at school, it's the one thing I have, so right after when there were loads of people at home I could get out of the house and focus on something else," says Nikita.  。

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Nikita said she didn't expect to get such good grades, and she would have been happy with lower results. Asked how Martyn would have responded to her fantastic news, Nikita said he'd have been really happy. 。

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"He'd just be really proud," she said. "And he'd have been tweeting about it," said Nikita.。"He'd just be really proud," she said. "And he'd have been tweeting about it," said Nikita.。What an incredible young woman. 。Featured Video For You 。Dear internet, Emma Watson needs your help。