But unlike most carefree 4-year-olds, Charmaine has stage four cancer and is fighting for her life.
A rib cage that appeared to be higher on one side first alerted her mother, Ms Cynthia Lim, 29, that something wasn't quite right with her daughter.
A 12cm tumour was found growing in Charmaine's right adrenal gland, which is located above the kidney. The diagnosis came after several blood tests and scans at the KK Women's and Children's Hospital (KKH) in February.
The high-risk cancer was found to have spread to her bone marrow and bones.
Charmaine was diagnosed with stage four neuroblastoma, a kind of cancer that occurs in infants and kids.
This form of cancer usually arises in the adrenal glands or in the nervous system related to the adrenal glands.
Charmaine is undergoing treatment at the National University Hospital (NUH).
So far she has undergone four rounds of chemotherapy with surgery to remove the tumour coming up next week.
And if she continues with her treatment in Singapore, she will also undergo a bone marrow transplant after her fifth round of chemotherapy next month.
There is an alternative form of treatment offered in the US, but it is not certain whether Charmaine will be able to get it.
Nausea
Meanwhile, she has to grapple with difficult lifestyle changes.
She no longer mixes freely with other kids in the playground or attends nursery school, because her lowered immunity puts her at high risk of falling ill.
The chemotherapy has caused her once lush locks to fall out and her skin to darken. In addition, she suffers from bouts of nausea and vomiting.
Stage four neuroblastoma among children is rare, but Charmaine is not the youngest such patient in Singapore.
Dr Chan Mei Yoke, senior consultant of haematology and oncology services at KKH, said one baby had stage 4S neuroblastoma when it was born at the hospital a few years ago. The 4S category refers specifically to newborns with the condition.
She said there are about three to six new neuroblastoma cases a year in Singapore.
'This makes up roughly 6 per cent of all childhood cancers,' she said. 'Leukaemia is the most common form of cancer in children here.'
An NUH spokesman said its youngest patient is a 4-month old baby with brain tumour.
'Neuroblastoma is a very rare cancer. Leukaemia and brain tumours are the top two childhood cancers.'
The spokesman added that while neuroblastoma is rare, stage four is unfortunately common in those that suffer from this form of cancer.
She noted: 'It occurs about 41 per cent of the time.'
Stage 4S, which occurs in infants, in comparison, occurs in about six per cent of all kids with neuroblastoma, she said.
The condition is usually diagnosed by the age of 5 and hardly occurs after the age of 10, said the spokesman.
Despite the treatments, the odds of Charmaine's survival stands at a slim 20 per cent, according to her medical report.
Now her mother is 'hoping against hope' to boost her daughter's chances of survival.
Ms Lim is pinning her hopes on the alternative treatment called 3F8, which Charmaine's NUH medical report noted, could help boost her chances of survival to as much as 40 to 50 per cent.
But this treatment is available only at the Memorial Sloan-Kettering Cancer Center in New York.
It's also very costly - US$350,000, which is slightly more than $500,000.
That's a hefty sum for Ms Lim, a divorcee who quit her project management job at a water treatment company to look after her daughter full-time.
She is barely coping with the NUH medical bills which is estimated at about $80,000.
Next month or in August, Charmaine would either have to proceed with the bone marrow transplant locally or head overseas for several doses of the 3F8 drug.
Ms Lim is hoping to raise the $500,000 by then and is seeking help.
Her strong desire to save her daughter at all costs has changed her, she said.
'In the past I was more proud. I used to think that I could solve any problem on my own, but now I'm literally begging people to help me,' Ms Lim said.
She wants to do everything possible to keep her daughter alive. Most of all, she encourages Charmaine to fight on.
Perhaps Charmaine's fighting spirit is best seen when her mother talks about the 'monster' inside her.
She always replies: 'Yes, I will fight with the monster.'
She gets by on donations, savings, but needs more
AS a mother, Ms Cynthia Lim had little interest in cancer - until her daughter was diagnosed with it.
'When I first found out (about the cancer), it was terrible,' she said.
'I couldn't stop crying because the fear of losing her is very great.
'Before this, cancer was a very distant topic to me, something which I didn't know much about.'
Ms Lim lives in a four-room HDB flat in Punggol with Charmaine, her son, Jase, 5, her cabby father, 67, and mother, 66, and a younger brother, 27, a civil servant.
Since quitting her job, she gets by on her savings and her ex-husband's monthly maintenance payments of $1,300.
With donations from friends and well-wishers amounting to about $50,000 and her own Medisave, footing Charmaine's local medical bills seems achievable.
But Ms Tan hopes to raise the $500,000 needed to seek treatment in New York to improve Charmaine's chances of survival.
To update friends on Charmaine's situation, as well as to seek donations, Ms Lim and three friends set up a blog, www.ourfeistyprincess.com, in March.
Friends like Ms Josse Tan, 37, are helping Ms Lim with the fund-raising.
She said: 'I told Cynthia that whatever is within your control, you do it. Whatever is not within your control, let it go.'
Charmaine has not let her illness and medical treatment affect her bubbly spirit and sweet nature.
While she was shy and wouldn't answer questions from this reporter, her personality shone through in other ways.
Her playful side came out when she bargained with her mother for more sweets.
Ms Lim said: 'Two for you and two for kor kor (Hokkien for big brother).'
But Charmaine responded coyly: 'No, four (for) me and four for kor kor.'
Higher survival rates with drug
THE treatment that could potentially double Charmaine's chances of survival involves giving several doses of a drug known as 3F8, which is produced by the white blood cells of mice.
These antibodies are given intravenously to a patient and will circulate in the bloodstream till they attach to a neuroblastoma cell.
The patient's own immune system will then attack and kill the neuroblastoma cell.
The treatment has been used in more than 500 patients since 1987.
Charmaine's medical report from NUH has noted that this therapy provides such patients with a higher survival rates of up to 40 to 50 per cent.
