Lullaby is a personalized sleep training service and platform for parents and their newborns.


Sleep deprivation is a significant pain point for new parents. However, solutions are hard to come by, especially when conservative Japanese parents look down on the concept of sleep training. This prevents new parents (more often women) from achieving fullness of life due to lack of restful sleep.The challenge for Lullaby is to create a scalable, but customizable experience that works for the dynamic lifestyle of new parents.


Lullaby aims to create and communicate a new culture of “sleep training” to parents in the Japanese market. Lullaby is looking to show how sleep training is healthy and beneficial for both babies and parents. The opportunity for Lullaby is to be a first-to-market mover on sleep training in Japan.

How Founder Yukari Tago’s Path to Building Confidence for Parents has Defined Lullaby’s North Star

Words by Kyra Yamamoto

A few years ago, if you had asked Yukari Tago if she would ever be a founder, she would likely have shied away from the idea. The birth of Yukari’s son changed everything for her, from her personal life to her professional career. It’s these life changes that brought Yukari to share her idea with Moon.

“When my son was just 6 months old, he would wake up every three hours at night. It was one of my hardest experiences mentally and physically as a first time parent. I couldn’t sleep. Mentally, I really wanted to wake up and take care of my son, but I just couldn’t. That really ruined my new life as a parent. The other thing that really devastated me was realizing that there was not a concrete solution for getting my son to sleep properly. I realized that in Japan, no one could really help me with my son. However, in America, where I gave birth, there was an entire culture around sleep training and sleep consultants who could help me in the position I was in. That culture has never really existed in Japan. I still don’t think it does,” Yukari explains. “My personal experience of sleep training with a sleep consultant and having that supportive environment really helped me as a new parent. I wanted that for Japan and I really wanted to localize it to fit the Japanese market.”

Yukari joined Moon on September 1, 2019 from the Healthcare & Service Business Unit within Mitsui & Co. When she first pitched to the Moon Committee, her original idea was a product that would help babies sleep more soundly. After learning more about her target users and their needs, the vision for Lullaby evolved too.

“At the very start, I just wanted to release a product that would help put babies to sleep. That was our product vision: If you buy this, your baby is going to go to sleep. However, after consulting many moms and dads, I began to realize what they really wanted, and what they were really scared of, wasn’t just putting their babies to sleep. Some moms even came to us when their babies were sleeping up to ten hours a night! No matter how well or poorly their babies were sleeping, they were still afraid they were doing something wrong as new parents.

What these parents really wanted was confidence. They wanted someone to tell them, “Yes! Your kid is fine. You’re doing great!” They wanted reassurance to build their confidence to make stronger decisions as parents. That changed my entire vision for Lullaby: to build confidence through sleep training.”

What makes Yukari stand out as an entrepreneur is her dedication to building up parent’s confidence through sleep training as much as it has built up hers. You can’t help but smile when seeing her light up as she talks about the moms and sleep consultants she’s worked with so far. “When I was first deciding whether to share my idea with Moon or not, there were so many decisions I had to consider. However, I quickly realized how lucky I was to receive as much support as I did to join Moon from friends, family and colleagues. Everyone has been very supportive, especially all the sleep consultants who had decided to join Lullaby. One or two of them even gave up their full-time jobs to be 100% on board with Lullaby. There’s no point in turning back for me or to stop pursuing Lullaby. My husband, my old department, Moon, my team… all of these people have helped keep me going.”

Yukari’s dedication to Lullaby’s growth over the past year despite the impact of a pandemic shows her strength as an up and coming founder. The Lullaby Beta app was released in early December with the official app launching on March 25, 2021. In addition, the team behind Lullaby created and launched a sleep consultant course, and has since grown their sleep consultant community to 50 consultants.

“Since launch, we have received a 98% satisfaction rate from the sleep training consultations. One thing that’s really clear is that once you receive a consultation, learn the right rhythm for your baby and are consistent, there is a high probability you will see a positive change in your baby’s sleep. I think the 98% satisfaction rate has proven that the consultation and app work, but the hard part is having parents take the first step to try out the sleep training, since it’s still not common in Japan. But once they try it they can understand it actually works. That's currently our biggest challenge.”

“Seeing sales come in has built up my confidence too. I've always believed that if you have a service that is generating sales while also making a positive impact within the community, that is success. Sales are a great point to better understand your market fit. Watching sales come in, even if they’re small, makes it feel like it’s all worth it. There’s a little light I can see that maybe this is the right way, let’s keep going.”

The amount of growth Yukari has experienced since sharing her idea on SMAP has allowed her to grow more confident, both personally and professionally. “I don’t think I would have been able to build a company on my own from scratch. Moon has been by my side, giving me lots of opportunities. Anyone who has a great idea and wants to deliver that, Moon gives a great role to support that lifestyle and make it all possible.”

“What parents really wanted was confidence. They wanted someone to tell them, ‘Yes! Your kid is fine. You’re doing great!’”


Yukari Tago

Healthcare and Service Business Unit Mitsui & Co., Ltd.

Moon Team:

Adam Bildersee Asami Kawanishi Jeff Chen Kyra Yamamoto Lung Tsai (Ryu) Liu Masao Fujii Ryoji Mitsuhashi Sharon Peng Shingo Nishimori (Mori Mori) Sho Nonaka (Nonasho)

Executive Sponsor:

Jeremy Clark

Where Lullaby is today:

The Lullaby service is operating consistently and achieving revenue, with over 10 certified sleep consultants advising dozens of member families (from >4,000 app downloads) on healthy sleep habits for their babies. User research has identified key features of the Lullaby service that deliver unique value, including the adaptive sleep schedule. The EIR and team are currently developing the medium-term product strategy to provide the platform for robust growth and profitability.



Download Lullaby on iOS and Android






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