Mae'r haul hwyr yr haf yn bwrw golau cynnes dros gaeau’r ysgol uwchradd wrth i fyfyrwyr ruthro heibio, gyda chynnwrf y gem fawr ar wefusau pawb.

The late summer sun cast a warm light over the fields of the ysgol uwchradd, as students rushed by, the excitement of the big game on everyone's lips.

Roedd Branwen yn sefyll yn y coridor prysur, ei llygaid yn canolbwyntio ar y nod clir: datrys dirgelwch pwysig iawn, dirgelwch a oedd yn angherddol i ysgol gyfan: diflaniad gwisg y masgot.

Branwen stood in the busy corridor, her eyes focused on a clear goal: solving a very important mystery, a mystery that intrigued the entire school: the disappearance of the mascot's costume.

Roedd Gareth, y masgot caredig ond trapsglud, yn bryderus iawn.

Gareth, the beloved but clumsy mascot, was very anxious.

Byddai’r gêm hebddo yn ergyd drom i’r ysgol.

The game without him would be a heavy blow to the school.

Roedd ei feddyliau’n cuddio y tu ôl ei lygaid gwyllt, ond roedd Branwen yn gweld hynny.

His thoughts were hidden behind his wild eyes, but Branwen could see it.

Roedd hi’n berson sy’n gweld popeth.

She was someone who noticed everything.

Felly, penderfynodd Branwen gyda chymorth ei ffrind orau, Rhiannon, ymchwilio i’r mater gan ddefnyddio’r flwyddyn uchaf ei gallu.

So, Branwen decided, with the help of her best friend, Rhiannon, to investigate the matter using the full extent of their abilities.

"Fe wnawn ni ddarganfod, Gareth," meddai Branwen, yn cymryd anadl ddofn.

"We will find out, Gareth," said Branwen, taking a deep breath.

Roedd Rhiannon yno hefyd, ychydig yn amheus, ond yn barod i gefnogi eu hymdrechion.

Rhiannon was there too, a little skeptical, but ready to support their efforts.

"Ond bydd raid i ni fynd â’r ymdrech hon o ddifrif.

"But we'll have to take this effort seriously."

"Ers wythnosau, roedd pawb wedi bod yn sôn am y gem a oedd i ddod.

For weeks, everyone had been talking about the upcoming game.

Roedd hi’n uchafbwynt tymor yr haf.

It was the highlight of the summer season.

Heb y masgot, roedd yr ysbryd yn y dirlawnder.

Without the mascot, the spirit was deflated.

Felly, penderfynodd Branwen a Rhiannon sgipio ymarfer corff am unwaith ac ymuno â Gareth i ymchwilio.

So, Branwen and Rhiannon decided to skip gym practice for once and join Gareth to investigate.

Wrth iddynt fynd trwy wahanol gorneli’r ysgol, fe wnaethant stopio ger yr hen ystafell storio, man lle na fyddai neb yn meddwl edrych.

As they went through different corners of the school, they stopped near the old storage room, a place where no one would think to look.

Yn sydyn, canfu Branwen ffabrig rhwygo yn y drws.

Suddenly, Branwen found torn fabric at the door.

Roedd hi'n ddarn o’r wisg masgot - ei sbin sydd fel cydio mewn cyfrinach.

It was a piece of the mascot costume - a spin like holding a secret.

Roedd y darn hwn yn arwydd i’w dilyn.

This piece was a clue to follow.

Wrth i Branwen roi'r darn yn ei phoced, clywiasant gamau traed yn agosáu, gan wneud i’w calonnau guro’n gyflym.

As Branwen put the piece in her pocket, they heard footsteps approaching, making their hearts beat quickly.

Ond roedd hi'n rhy hwyr i gamu yn ôl.

But it was too late to step back.

Fe sylweddolodd Branwen yn gyflym mai eu gweld oedd rhaid.

Branwen quickly realized they needed to face whatever was coming.

"Rydyn ni’n dod o hyd i hyn, a dyna fydd yn gwneud iawn am hyn," meddai Branwen, yn troi i Gareth ac yna Rhiannon.

"We're finding this, and that's what will make up for it," said Branwen, turning to Gareth and then Rhiannon.

Roedd moment o wefr yn dod â phenderfyniad newydd i’r amlwg.

A moment of exhilaration brought a new determination to light.

Fe ddychwelodd y tri i ganol y digwyddiadau y diwrnod cynt, lle roedd ysgol gyferbyn wedi trefnu cyfarfod gyda’r trefnwyr.

The trio returned to the events of the previous day, where a neighboring school had organized a meeting with the organizers.

Sylweddolodd Branwen fod un o’r myfyrwyr hynny, yn gwbl ddiniwed wrth un golwg, wedi bod yn cuddio’r darn o honno er mwyn chwarae tric.

Branwen realized that one of those students, seemingly innocent at first glance, had been hiding the piece as a prank.

O ymdrech ddiflino a dewrder, dychwelodd Branwen y gwisg yn brydlon i Gareth i’w wisgo.

With tireless effort and bravery, Branwen promptly returned the costume to Gareth to wear.

Roedd y masgot yn dod yn fyw wrth iddo ddod allan ar y cae, mae’r plant yn gweiddi’n llawen.

The mascot came to life as he emerged onto the field, with the kids cheering joyously.

Gyda’r gêm yn nesáu, a’r ysgol bellach mor fywiog â'r haul, roedd Branwen yn gwybod bod dim byd yn amhosib pan fydd y galon a'r meddwl ar y cyd.

With the game approaching, and the school now as lively as the sun, Branwen knew that nothing was impossible when the heart and mind worked together.

Cafodd ei chydnabod am ei hymdrechion, ac ymhiliodd hi i glybiau dealltwchan yr ysgol.

She was acknowledged for her efforts and was welcomed into the school's intelligence clubs.

Wrth adael y cae, nawr yn hyderus gyda gwybod y gall ddatrys unrhyw ddirgelwch, gwelodd Branwen bod dyfodol llesniol yn aros iddi.

As she left the field, now confident with the knowledge that she could solve any mystery, Branwen saw a bright future awaiting her.

Roedd hi’n gwybod, beth bynnag fyddai'n dod, ei bod hi erioed wedi bod mor barod.

She knew, whatever would come, that she had never been so ready.