Naze Toudouin Seiya 16-sai wa Kanojo ga Dekinai no ka?  

Why Can't Seiya Todoin, 16-Year-Old, Get a Girlfriend?, Why Can't I Get a Girlfriend?, なぜ東堂院聖也16歳は彼女が出来ないのか？, Why Can't Seiya Todoin, 16-Year-Old, Get a Girlfriend?

Seiya Toudouins inability to find a romantic partner has caused him great frustration despite his academic achievements, athletic abilities, and good looks. He has never had a girlfriend after 16 years of life, and every time he comes close, he is left with painful memories. Determined to achieve this goal during high school, Seiya sets out on a challenging journey due to his inexperience and social awkwardness. However, he remains committed to finding a romantic partner based on his strong belief that it's essential for his happiness. As he continues on this path, the journey may provide him with a deeper understanding of himself than any mirror could offer.

Toudouin Seiya was re-serialized in Japanese and English (as Why Cant I Get a Girlfriend?) through DeNAs Manga Box app from May 23, 2014 to August 28, 2015. During the Manga Box serialization, the original 39 chapters were split into 67.The series inspired a 9-episode NBN TV drama series that aired from October 21 to December 16, 2014.