Suggestion: Use "1girl" tag instead of "1boy". Idk I trained it on 1boy, but he just looks worse with it in my opinion. You can try of course if you want.

Yamato Takeru

Weight: 1.0

Trigger: Yamato

Character:

Yamato, orange eyes, black hair,

Disclaimer: Hairstyles are different in each Stage, so choose whichever you want.

1st Stage Outfit:

Takeru_1st, single braid, ahoge, japanese clothes, long sleeves, turtleneck, long sleeves, wide sleeves, white outfit,

2nd Stage Outfit: (Why the heck is it a School Uniform???)

Takeru_2nd, short hair, cabbie hat, glasses, red-framed eyewear, semi-rimless eyewear, black headwear, white shirt, collared shirt, black blazer, open blazer, dark blue vest, vest, blazer, red necktie, school uniform, plaid pants, long sleeves, black sleeves,

3rd Stage Outfit:

Takeru_3rd, long hair, ahoge, black sash, jewelry, white kimono, black pants, white pelvic curtain, pleated pants, detached sleeves, white sleeves, black sleeves, wide sleeves, covered shoulders, necklace, japanese clothes, 

4th Stage Outfit:

Takeru_4th, singe hair bun, earrings, hair ornament, alt sash, teal sash, halter dress, two-tone dress, white dress, teal dress, shoulder armor, halterneck, red necklace, detached sleeves, jewelry, white cape, gauntlets, black sleeves, black skirt, white skirt, pleated skirt, long skirt,

The results of your generations are dependent on the additional LoRAs, weights, and models you use, so it may not work or come out as consistent as my sample images.