Oseam

They both tell the story of sibling love, the innocence of children and their games and the often tragic lives of orphans. While Grave of the fireflies is based on facts of the lives of war children, Oseam is based on a legend/fairy tale. Oseam doesn't have the feeling of a brutal reality as Grave of the fireflies and has a more religious tone in the story using the ideas and believes of Buddhism. Simply put, they both are beautiful and tragic stories, and if you like the one, you'll definitely like the other 

These tear-jerking dramas are based on classic tale in each country. Orphan/s accompanied by a dog. A heartwarming, tragic story take a place in countryside on winter. Similar atmosphere, never give up hope, even there isn't much.  

Love, warm hearts and sincere feelings. No matter if love is between man and woman, brother and sister or mother and child, 'cause both movies are about Love that is pure and innocent, Love with a capital "L" (though Oseam is more about Love than 5cm). Sentimentality is included, too :) .